JP2019070737A - Observation device, focusing control method, and program - Google Patents

Abstract

To provide a technique that performs contrast AF at high speed with high accuracy using a few computational resources.SOLUTION: A microscope device 1 includes a processing unit 40 for performing focusing control processing. The processing unit 40 computes an evaluation value having positive correlations with both contrast of an image and size of a focusing target area on the basis of data corresponding to the focusing target area of data on the image of a sample S in the focusing control processing. Furthermore, the processing unit 40 compares the evaluation value with at least one threshold value corresponding to the size of the focusing target area and having a positive correlation with the size of the focusing target area.SELECTED DRAWING: Figure 1

Description

  The disclosure of the present specification relates to an observation apparatus that performs autofocus (hereinafter, referred to as AF) by a contrast AF method, a focus control method, and a program.

  In recent years, a microscope system has an AF function in order to perform an observation operation efficiently. Although various methods exist for AF, an AF method called contrast AF is typical as an AF method employed for a microscope system provided with an imaging device such as a CCD or CMOS.

  In contrast AF, an AF evaluation value that has a positive correlation with the contrast of the image is calculated from the image data, and the position where the AF evaluation value is the highest is detected as the in-focus position. Such contrast AF is employed not only in a microscope system but also in a camera or the like. For example, Patent Document 1 describes a microscope performing contrast AF, and Patent Document 2 describes a camera performing contrast AF.

  Various methods have been proposed as methods for calculating AF evaluation values in contrast AF, but the method of calculating using the sum of squares of differences between pixel values of adjacent pixels, that is, Brenner gradient of shift amount 1 is generally used. It is

  However, since Brenner gradient has a larger value as the number of pixels to be calculated (hereinafter referred to as AF target pixels) increases, in many cases, Brenner gradient itself is used as an AF evaluation value in contrast AF. Instead, the normalized value of Brenner gradient using the number of pixels of the AF target pixel is used as an AF evaluation value.

Patent No. 588 1 445 Patent No. 5478213 specification

  By the way, the above-described Brenner gradient calculation processing and normalization processing include an operation that consumes a relatively large amount of calculation resources such as "square" and "division". In order to speed up AF, these processes performed every time an image is acquired can be one factor that limits the speeding up.

  Based on the above-mentioned actual situation, an object according to one aspect of the present invention is to provide a technology for realizing high-speed and high-precision contrast AF with a small number of calculation resources.

  An observation apparatus according to an aspect of the present invention is an observation apparatus including a processing unit that performs focusing control processing. In the focusing control process, the processing unit positively correlates with both the contrast of the image and the size of the focusing target region based on data corresponding to the focusing target region of the data of the sample image. And calculating the evaluation value as at least one threshold according to the size of the focusing target area, the at least one threshold having a positive correlation with the size of the focusing target area, and ,Compare.

  The focusing control method according to an aspect of the present invention is the focusing control method performed by the processing unit of the observation device, and the focusing control method of the image is performed based on data corresponding to the focusing target area among the data of the image of the sample. An evaluation value having a positive correlation with both the contrast and the size of the focus target area is calculated, and the evaluation value is at least one threshold corresponding to the size of the focus target area, the focus target Compare with the at least one threshold that is positively correlated with the size of the region.

  A program according to an aspect of the present invention is characterized in that, in a processing unit for performing focusing control processing included in an observation apparatus, the contrast of the image and the contrast of the image are determined based on data corresponding to a focusing target area An evaluation value having a positive correlation with both of the sizes of the focusing area is calculated, and the evaluation value is at least one threshold according to the size of the focusing area, and the size of the focusing area And the process of comparing with the at least one threshold value having positive correlation with.

  According to the above aspect, it is possible to provide a technology for realizing high-speed and high-precision contrast AF with less computational resources.

It is a figure which illustrated composition of a microscope system concerning a 1st embodiment. It is a figure for demonstrating a peak detection AF system. It is a figure for demonstrating false focusing. It is a figure for demonstrating a noise determination threshold value. It is a figure for demonstrating a focus position vicinity determination threshold value. It is a figure for demonstrating the relationship between the size of a focusing object area | region, and an evaluation value. It is a flowchart of focusing control processing. It is a flowchart of a focusing determination process. It is a figure which illustrated composition of a microscope system concerning a 2nd embodiment. FIG. 2 is a diagram illustrating the configuration of a computer 90.

First Embodiment
FIG. 1 is a diagram illustrating the configuration of a microscope system according to the present embodiment. The microscope system shown in FIG. 1 includes a microscope device 1 which is an example of an observation device which performs contrast AF, a display device 70 which displays an image acquired by the microscope device 1, and an input device 80 which inputs commands to the microscope device 1. Have.

  The microscope apparatus 1 includes a stage 10 on which the sample S is mounted, an optical system 20 for forming an optical image of the sample S, and an imaging apparatus 30 for converting the optical image of the sample S into image data. The microscope apparatus 1 further includes a processing unit 40 that performs focusing control processing, a driving apparatus 50 that moves the focusing apparatus 60, and a focusing apparatus 60 that changes the distance between the stage 10 and the imaging target surface of the microscope apparatus 1. Have.

  The optical system 20 is, for example, an imaging optical system including an objective lens and an imaging lens, and projects an optical image of the sample S on the light receiving surface of the imaging device 30. The imaging device 30 is, for example, a digital camera including an imaging element such as a CCD image sensor or a CMOS image sensor. The imaging device 30 outputs the image data of the sample S to the processing unit 40.

  The processing unit 40 is, for example, an electronic circuit mounted in the housing of the microscope apparatus 1 and is, for example, an FPGA (Field Programmable Gate Array). The processing unit 40 includes an image transmission unit 41 and a focusing control unit 42. The image transmission unit 41 transmits the image data output from the imaging device 30 to the display device 70. The focusing control unit 42 performs focusing control processing described later.

  The driving device 50 is, for example, a motor driven by a pulse signal output from the processing unit 40. The focusing device 60 holds an optical system 20 and an imaging device 30. The focusing device 60 moves along the optical axis direction of the objective lens included in the optical system 20 by the power of the driving device 50.

  The display device 70 is, for example, a liquid crystal display, but may be an organic EL (OLED) display, a CRT display, or the like. The input device 80 is, for example, a keyboard, but may be a mouse, a joystick, a touch panel, or the like.

  The microscope apparatus 1 configured as described above acquires an image of the sample S at each position of the focusing device 60 while moving the focusing device 60. Then, the position of the focusing device 60 at the time of acquiring the highest contrast image is detected as the in-focus position, and the focusing device 60 is moved to the in-focus position. Thereby, the contrast AF is realized. Hereinafter, the process of acquiring an image while moving the focusing device 60 to detect the in-focus position is referred to as an AF search.

  The contrast AF performed by the microscope apparatus 1 will be described more specifically. First, a method of calculating an AF evaluation value used in contrast AF will be described.

  In contrast AF, the contrast of an image is determined by the level of an AF evaluation value (hereinafter simply referred to as an evaluation value) calculated using image data. The evaluation value is a value having a positive correlation with the contrast of the image, and is calculated each time the imaging device 30 acquires an image in an AF search. If the evaluation value calculation process performed each time an image is acquired is a heavy process using a large amount of computational resources, speeding up of AF will be limited.

  Therefore, in the microscope apparatus 1, the processing unit 40 performs both of the contrast of the image and the size of the focus target area in the focus control processing based on the data corresponding to the focus target area of the image data and positive. Calculate an evaluation value having a correlation. The focusing target area is the area of interest if the area of interest (ROI) is specified and AF is performed. The region of interest may be designated by the user using the input device 80, or may be automatically designated by the microscope device 1. If the AF is performed without specifying the region of interest, it means the field of view of the microscope apparatus 1.

  Since the processing unit 40 calculates an evaluation value having a positive correlation with the size of the focus target area, the normalization process (division) is performed in the process of calculating the evaluation value, unlike the case where the conventional evaluation value is calculated. It does not happen. Therefore, the consumption of computational resources can be suppressed. Further, as the evaluation value has a positive correlation with the contrast of the image, the level of the contrast of the image can be determined by the evaluation value, as in the conventional evaluation value.

Specifically, the processing unit 40 may calculate the evaluation value using the following expression (1). Here, E is an evaluation value. I is a pixel value of each pixel corresponding to the focusing target area included in the image data. N and M are the number of rows and the number of columns of pixels (also referred to as AF target pixels) corresponding to the focus target area.

If the focusing target area is projected onto the 8 × 8 pixel, the equation (1) is expanded as the following equation (1-1).

  By calculating the evaluation value using equation (1), the evaluation value can be calculated without performing operations such as “square” or “division”.

The processing unit 40 may also calculate the evaluation value using the following equation (2). That is, the evaluation value may be a so-called Brenner gradient of shift amount 1.

  It should be noted that comparing equation (1) with equation (2), equation (1) which does not include the “square” operation is preferable in that it consumes less computational resources and enables faster calculation. .

  FIG. 2 is a diagram for explaining the peak detection AF method. FIG. 3 is a diagram for explaining false focusing. FIG. 4 is a diagram for explaining the noise determination threshold. FIG. 5 is a diagram for explaining the in-focus position vicinity determination threshold value. Next, the threshold used for contrast AF will be described with reference to FIGS. 2 to 5. This threshold is a threshold for the evaluation value, and is used to improve the performance of AF, mainly the accuracy of AF and the speed of AF. In the following, a peak detection AF method, which is a type of contrast AF, will be described as an example.

  The peak detection AF method is a method of contrast AF in which the peak position of the evaluation value detected during the AF search is detected as the in-focus position. More specifically, while the focusing device 60 moves a predetermined search range from the start position Zstart toward the end position Zend, an image is obtained at each position (referred to as a sampling point) to calculate an evaluation value. The latest evaluation value calculated is compared with the maximum evaluation value at that time, and if the latest evaluation value is larger than the maximum evaluation value at that time, the maximum evaluation value is updated with the latest evaluation value. Then, when the latest evaluation value becomes lower than a predetermined ratio (for example, 25%) with respect to the maximum evaluation value at that time, when an image is obtained in which the maximum evaluation value at that time is calculated The position of the focusing device 60 is detected as the in-focus position.

  FIG. 2 shows an example in which the evaluation value decreases by more than 25% with respect to the maximum value at position Z1 (see sampling point P1) while the focusing device 60 is moving from the start position Zstart to the end position Zend. It is done. In this case, the position Zpeak (refer to the sampling point Pp) indicating the largest evaluation value Epeak at that time is detected as the in-focus position, and the AF search is ended. In the peak detection AF method, since the AF search can be aborted before the focusing device 60 reaches the end position Zend, the speed of AF can be increased as compared with the case where the AF search is continued to the end position Zend.

  On the other hand, in the peak detection AF method, noise caused by disturbance light is generated in the electric circuit, and an event called false focusing may occur due to the noise. This is based on the premise that the contrast AF calculates a larger evaluation value as the sampling point approaches the in-focus position, but noise may cause a peak (maximum value) of the evaluation value at a position other than the in-focus position. It is.

  FIG. 3 shows an example in which the evaluation value at the position Z2 (sampling point P2) decreases by more than 25% with respect to the evaluation value Efake at the position Zfake (sampling point Pf). In this case, the peak position Zfake generated due to the influence of noise is erroneously detected as the in-focus position, and the AF search is ended. Such false focusing tends to occur particularly at a position away from the in-focus position. This is because, if affected by noise at a position away from the in-focus position, the evaluation value calculated at the adjacent sampling points is small or the evaluation value can not be calculated, and thus a peak that is greatly protruded tends to be easily generated. Therefore, even if the predetermined ratio is sufficiently large, an erroneous position is detected as the in-focus position.

  Therefore, in the microscope device 1, the processing unit 40 compares the evaluation value with the noise determination threshold Eth1 in the focusing control process, and the maximum evaluation used for peak determination according to the comparison result (first comparison result) You may update the value. The noise determination threshold Eth1 is a first threshold for the noise level in the microscope apparatus 1 and is a threshold for suppressing false focusing and improving the accuracy of AF.

  More specifically, when the latest evaluation value exceeds the noise determination threshold Eth1 in the focusing control process, the processing unit 40 determines that the latest evaluation value is higher than the maximum evaluation value at that time. If it is larger, the largest evaluation value is updated with the latest evaluation value. On the other hand, when the latest evaluation value is equal to or less than the noise determination threshold Eth1, the maximum evaluation value is not updated with the latest evaluation value. That is, no focus detection is performed.

  Thereby, as shown in FIG. 4, the range where the evaluation value is larger than the noise determination threshold Eth1 is the actual peak search range. For this reason, it is possible to avoid false detection of a peak due to a small evaluation value that may occur at a position away from the in-focus position as the in-focus position, and it is possible to significantly suppress the occurrence of false focusing.

  Further, in the microscope device 1, the processing unit 40 compares the evaluation value with the in-focus vicinity determination threshold Eth2 in the focusing control process, and controls the focusing device 60 according to the comparison result (second comparison result). You may Specifically, the moving speed or the moving amount of the focusing device 60 is changed according to the comparison result. The in-focus vicinity determination threshold Eth2 is a second threshold of the microscope apparatus 1 regarding the in-focus evaluation value level, and is a threshold for improving the accuracy and speed of the AF. It is desirable that the in-focus vicinity determination threshold Eth2 be a value larger than the noise determination threshold Eth1.

  More specifically, when the evaluation value exceeds the in-focus vicinity determination threshold Eth2 in the focusing control process, the processing unit 40 determines that the focusing device 60 is located in the vicinity of the in-focus position, The focusing device 60 is controlled at a small moving speed or moving amount. That is, the sampling points are closely provided. On the other hand, if the evaluation value is less than or equal to the in-focus determination threshold Eth2, the focusing device 60 determines that the focusing device 60 is located far from the in-focus position, and controls the focusing device 60 at a large moving speed or moving amount. That is, the sampling points are set roughly.

  As a result, as shown in FIG. 5, since the focusing device 60 is in the low speed search range in which the focusing device 60 moves slowly, more sampling is performed near the focusing position. Therefore, it is possible to detect the peak position of the evaluation value with higher accuracy, and the accuracy of AF is improved. In addition, since the area away from the in-focus position is a high-speed search range in which the focusing device 60 moves fast, the processing time in the area where the in-focus position does not exist can be shortened to speed up AF.

  Note that, in FIG. 5, by providing the low speed search range using the in-focus vicinity determination threshold Eth2, the in-focus position Zpeak 'at which a higher evaluation value Epeak' is calculated than when the low speed search range is not provided. An example of detection is shown.

  FIG. 6 is a diagram for explaining the relationship between the size of the focus target area and the evaluation value. Next, a method of calculating a threshold used in contrast AF will be described with reference to FIG.

  By appropriately setting the threshold as described above, the accuracy and speed of contrast AF can be improved. However, since the evaluation value calculated by the processing unit 40 has a positive correlation with both the contrast of the image and the size of the focusing target area, as shown in FIG. Even in the case where the evaluation is performed, the evaluation value increases in accordance with the size of the focusing target area. Therefore, using a constant threshold regardless of the size of the focusing area causes a situation where the focusing area is appropriate for one size, but not appropriate for other sizes. I will.

  Therefore, in the microscope device 1, the processing unit 40 calculates a threshold according to the size of the focusing target area in the focusing control process. Specifically, at least one threshold (for example, a noise determination threshold or an in-focus position determination threshold) having a positive correlation with the size of the focusing target area is calculated. More specifically, in the focusing control process, the processing unit 40 acquires size information regarding the size of the focusing target area, and calculates at least one threshold based on the size information.

  The processing unit 40 can set an appropriate threshold for the evaluation value having a positive correlation with the size of the focusing target area by calculating the threshold having a positive correlation with the size of the focusing target area. .

In the case where the evaluation value is calculated by, for example, the above-described equation (1), for example, the following equation (3) may be used as a calculation equation of the threshold. Here, Eth is one of at least one threshold. ΔI is a dynamic range of image data. M is the number of rows of pixels corresponding to the focusing target area. N is the number of columns of pixels corresponding to the focusing target area. K is a threshold coefficient.

  By calculating the threshold value using equation (3), both the evaluation value and the threshold value have a proportional relationship with the size of the focusing target area. For this reason, since the relationship between the evaluation value and the threshold is also maintained constant regardless of the size of the focusing target area, it is possible to set an appropriate threshold for the evaluation value.

  FIG. 7 is a flowchart of focusing control processing. FIG. 8 is a flowchart of the in-focus determination process. The focusing control process performed by the processing unit 40 will be specifically described with reference to FIGS. 7 and 8.

  When the user of the microscope system instructs the start of the contrast AF using the input device 80, the processing unit 40 (focusing control unit 42) starts the focusing control process shown in FIG.

  First, the processing unit 40 sets a region of interest (ROI) (step S10). Here, the processing unit 40 may set, for example, a region on the sample S designated by the user using the input device 80 while viewing the image displayed on the display device 70 as the region of interest.

  Next, the processing unit 40 calculates a threshold (step S20). Here, the processing unit 40 is at least one threshold corresponding to the size of the region of interest (focusing target region), and at least one threshold having a positive correlation with the size of the region of interest (focusing target region) calculate. For example, the processing unit 40 acquires size information on the size of the region of interest (for example, the number of pixels of the region on the imaging device 30 onto which the region of interest is projected), and calculates at least one threshold based on the size information. May be More specifically, the above-described noise determination threshold Eth1 and in-focus position vicinity determination threshold Eth2 may be calculated using the above-described equation (3). For example, the noise determination threshold Eth1 may be calculated using the threshold count k1, and the in-focus position vicinity determination threshold Eth2 may be calculated using the threshold count k2. The threshold counts k1 and k2 have a relationship of k1 <k2. For example, 10, 30 etc. may be sufficient.

  When the threshold is calculated, the processing unit 40 starts the in-focus determination process shown in FIG. 8 (step S30). In the focusing determination process, the processing unit 40 first moves the focusing device 60 (step S31). Here, the processing unit 40 moves the focusing device 60 at a speed or movement amount according to the setting. The setting of the initial state is a setting for moving at a relatively high speed, and the processing unit 40 moves the focusing device 60 to the start position of the AF search.

  When the focusing device 60 moves, the processing unit 40 controls the imaging device 30 to image a sample (step S32). Then, when receiving the image data from the imaging device 30, the processing unit 40 calculates an evaluation value (step S33). Here, the processing unit 40 calculates an evaluation value using, for example, Equation (1) based on data corresponding to the region of interest of the image data received in step S32.

  When the evaluation value is calculated, the processing unit 40 compares the evaluation value with the threshold (step S34), and performs processing according to the comparison result (step S35). For example, when the evaluation value calculated in step S33 is larger than the noise determination threshold Eth1 calculated in step S20, the processing unit 40 determines the peak if the evaluation value is larger than the maximum evaluation value at that time. Update the maximum rating value used. On the other hand, if the evaluation value is less than or equal to the noise determination threshold Eth1, the maximum evaluation value is not updated. Further, the processing unit 40 changes the setting of the moving speed or the moving amount of the focusing device 60, for example, according to the comparison result of the evaluation value and the in-focus position vicinity determination threshold Eth2 calculated in step S20. Specifically, when the evaluation value is larger than the in-focus position vicinity determination threshold Eth2, the setting is changed so that the moving speed or the moving amount of the focusing device 60 is reduced.

  After that, the processing unit 40 determines that the peak of the evaluation value is not detected if the evaluation value calculated in step S33 is not lower than a certain percentage than the maximum evaluation value at that time (step S36 NO), repeat the process from step S31 to step S36. On the other hand, if the evaluation value calculated in step S33 is lower than the maximum evaluation value at that time by more than a certain percentage, it is determined that the peak of the evaluation value is detected (YES in step S36), and the position of the peak is determined. A focus position is detected (step S37), and the focus determination process is ended.

  When the in-focus determination process ends, the processing unit 40 moves the focusing device 60 to the in-focus position detected in step S37 to bring the sample S into focus (step S40), and ends the in-focus control process. .

  In the microscope apparatus 1 that operates as described above, since an evaluation value having a positive correlation with the size of the focus target area is calculated, division is performed in the evaluation value calculation process performed each time an image is acquired during an AF search. No normalization is performed. Therefore, the evaluation value can be calculated at high speed with a small number of calculation resources.

  Further, in the microscope device 1, a threshold having a positive correlation with the size of the focusing target area is calculated, so that an appropriate threshold can be set for the evaluation value regardless of the size of the focusing target area. Therefore, it is possible to suppress false focusing by using the threshold and improve the AF accuracy, and to realize both AF accuracy and AF speed by controlling the focusing device 60 by using the threshold, etc. .

  Furthermore, in the microscope device 1, the threshold calculation process includes a multiplication process using size information of the focusing target area, but does not include a division using size information. Further, unlike the evaluation value calculation process, the threshold value calculation process is performed only once during the focusing control process. For this reason, it is possible to avoid a decrease in AF speed caused by the threshold value calculation process.

Therefore, according to the microscope apparatus 1, it is possible to realize high-speed and high-precision contrast AF with less calculation resources.
Second Embodiment

  FIG. 9 is a diagram illustrating the configuration of the microscope system according to the present embodiment. The microscope system according to the present embodiment is different from the microscope system according to the first embodiment in that a microscope apparatus 2 is provided instead of the microscope apparatus 1.

  The microscope apparatus 2 includes an optical system 120 instead of the optical system 20, a light detector 130 instead of the imaging apparatus 30, a processing unit 140 instead of the processing unit 40, and the focusing apparatus 60. It differs from the microscope apparatus 1 in that the focusing apparatus 160 is provided instead.

  The microscope apparatus 2 is a scanning microscope, and the optical system 120 is a scanning optical system provided with a scanner 121 that scans the sample S. The photodetector 130 is, for example, a photomultiplier (PMT), an avalanche photodiode (APD), or the like. An optical system 120 and a light detector 130 are held in the focusing device 160. The focusing device 160 changes the distance between the stage 10 and the imaging target surface of the microscope device 2

  The processing unit 140 is, for example, an electronic circuit mounted in the housing of the microscope apparatus 2 and is, for example, an FPGA (Field Programmable Gate Array). The processing unit 140 differs from the processing unit 40 in that the processing unit 140 includes an image construction unit 141 in addition to the image transmission unit 41 and the focusing control unit 42. The image construction unit 141 constructs an image based on the signal from the light detector 130 and the synchronization signal of the scanner 121, and outputs the image data to the image transmission unit 41 and the focusing control unit 42.

  Also in the microscope apparatus 2 configured as described above, the processing unit 140 (focusing control unit 42) performs the same focusing control processing as the processing unit 40, so that high-speed and high-precision contrast AF can be performed with less computational resources. It can be realized.

  The embodiments described above show specific examples for facilitating the understanding of the invention, and the embodiments of the present invention are not limited to these. The observation apparatus, the focus control method, and the program can be variously modified and changed without departing from the scope of the claims.

  In the embodiment described above, an example in which the processing unit is configured by the FPGA is shown, but the processing unit is not limited to the FPGA. The processing unit may be a microcomputer or the like incorporated in the microscope apparatus. In addition, when the microscope system includes a computer for control in addition to the microscope apparatus, the processing unit may be included in the computer 90 for control. The above-described focusing control process can perform contrast AF with less computational resources, and thus can be performed with an FPGA or the like which generally has less computational resources than a computer, but it is performed by executing a program with a computer May be

  FIG. 10 is a diagram illustrating the hardware configuration of the computer 90. The computer 90 is, for example, a standard computer, and as shown in FIG. 10, a portable storage medium drive into which the processor 91, the memory 92, the storage 93, the interface device 94, and the portable storage medium 96 are inserted. 95 is provided. These components are connected to one another by a bus 97. Note that FIG. 10 is an example of a hardware configuration of the computer 90, and the computer 90 is not limited to this configuration.

  The processor 91 is, for example, a central processing unit (CPU), a micro processing unit (MPU), a digital signal processor (DSP) or the like, and executes a program to perform focused control processing that is programmed. The memory 92 is, for example, a random access memory (RAM), and temporarily stores the program or data recorded in the storage 93 or the portable storage medium 96 when the program is executed. The storage 93 is, for example, a hard disk or a flash memory, and is mainly used to record various data and programs. The interface device 94 is a circuit that exchanges signals with devices other than the computer 90 (for example, the microscope device 1, the display device 70, the input device 80, and the like). The portable storage medium drive device 95 accommodates a portable storage medium 96 such as an optical disk or Compact Flash (registered trademark). The portable storage medium 96 has a role of assisting the storage 93.

  In the embodiment described above, a microscope apparatus is illustrated as an example of the observation apparatus, but the observation apparatus is not limited to the microscope apparatus. The observation device may be provided with a processing unit that performs focus control processing, and may be, for example, a camera such as a digital still camera or a digital video camera.

1, 2 microscope apparatus 10 stage 20, 120 optical system 30 imaging apparatus 40, 140 processing unit 41 image transmission unit 42 focusing control unit 50 driving device 60, 160 focusing device 70 display device 80 input device 90 computer 91 processor 92 memory 93 storage 94 interface device 95 portable storage medium drive device 96 portable storage medium 97 bus 121 scanner 130 light detector 141 image construction unit S sample

Claims (10)

The observation apparatus includes a processing unit that performs focus control processing.
In the focusing control process, the processing unit
An evaluation value having a positive correlation with both the contrast of the image and the size of the focusing region is calculated based on data corresponding to the focusing region among the data of the image of the sample,
The evaluation value is compared with the at least one threshold corresponding to the size of the focus target area and having a positive correlation with the size of the focus target area. Observation device. In the observation device according to claim 1,
In the focusing control process, the processing unit
Obtaining size information on the size of the focusing area;
The observation apparatus, wherein the at least one threshold is calculated based on the size information. In the observation device according to claim 1 or 2,
The at least one threshold includes a first threshold for noise level,
The processing unit updates the maximum evaluation value used for peak determination according to at least the first comparison result of the evaluation value and the first threshold in the focusing control process. . In the observation device according to any one of claims 1 to 3, further,
And a focusing device that changes a distance between a stage on which the sample is placed and a surface to be imaged of the observation device.
The at least one threshold includes a second threshold for a focus rating value level,
The observation device, wherein the processing unit controls the focusing device in the focusing control process according to a second comparison result of the evaluation value and the second threshold. In the observation device according to claim 4,
The processing unit changes the moving speed or the moving amount of the focusing device according to the second comparison result in the focusing control process. In the observation device according to any one of claims 1 to 5, further,
An imaging device for converting an optical image of the sample into data of the image;
The observation device, wherein the processing unit calculates the evaluation value using data of the image output from the imaging device. The observation device according to any one of claims 1 to 6.
The processing unit sets one of the at least one threshold as Eth, a dynamic range of data of the image as ΔI, a number of rows of pixels corresponding to the focusing target area as M, and the focusing. Assuming that the number of columns of pixels corresponding to the target area is N and k is a threshold coefficient, the above one threshold is
An observation device characterized by calculating The observation device according to any one of claims 1 to 7.
The processing unit sets the evaluation value to E, sets the pixel value of each pixel corresponding to the in-focus area included in the data of the image to I, and the number of rows of pixels corresponding to the in-focus area Where M is the number of columns of pixels corresponding to the in-focus area, and the evaluation value is
An observation device characterized by calculating A focusing control method performed by the processing unit of the observation apparatus
An evaluation value having a positive correlation with both the contrast of the image and the size of the focusing region is calculated based on data corresponding to the focusing region among the data of the image of the sample,
The evaluation value is compared with the at least one threshold corresponding to the size of the focus target area and having a positive correlation with the size of the focus target area. Method. A processing unit that performs focusing control processing of the observation device;
An evaluation value having a positive correlation with both the contrast of the image and the size of the focusing region is calculated based on data corresponding to the focusing region among the data of the image of the sample,
A process of comparing the evaluation value with at least one threshold corresponding to the size of the focusing target area and having a positive correlation with the size of the focusing target area is performed. A program characterized by