JP2893061B2 - Automatic focus adjustment device for microscope - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope automatic focus adjustment device for automatically adjusting the focus of an optical system in a microscope.

<Conventional technology> A conventional microscope has a stage that can move in each of the XYZ directions, and a light source for illumination is positioned behind the stage, and an optical system is positioned directly above the stage. The observation is performed by fixing the slide glass to be observed and adjusting the focus of the optical system.

The optical system 1 shown in FIG. 9 includes an objective lens 2 and a beam splitter 3, and has two optical paths 4, 5 having different optical path lengths.
CD line sensors 6 and 7 are arranged. In the figure, broken lines indicate the in-focus positions of the CCD line sensors 6 and 7, one of the CCD line sensors 6 is located at a distance -1 from the in-focus position, and the other is the in-focus position. Are arranged perpendicular to the optical axis at positions separated by a distance + l from the optical axis.

The image signals obtained by the respective CCD line sensors 6 and 7 are supplied to a focus detection circuit 17 having the configuration shown in FIG.

The focus detection circuit 17 shown in the figure includes differentiating circuits 8 and 9 for differentiating video signals from the CCD line sensors 6 and 7, and differentiating circuits.
Rectifier circuits 10 and 11 for rectifying the differential outputs of the rectifier circuits 8 and 9 and integration circuits 12 and 13 for integrating the rectified outputs of the rectifier circuits 10 and 11 under the control of the timing control circuit 14.

In the time chart shown in FIG. 11, A indicates the video signal from the CCD line sensors 6 and 7, B indicates the differential output from the differential circuits 8 and 9, C indicates the rectified output from the rectifier circuits 10 and 11, and E indicates the integrated output. The integrated outputs from the circuits 12 and 13 are shown respectively.
D is a gate signal output from the timing circuit 14, and integration processing is performed only during a period when the gate signal D is turned on.

Returning to FIG. 10, the A / D converter 15 converts the integrated output of each of the integrating circuits 12 and 13 into a digital quantity and supplies the digital quantity to the CPU 16. CPU16
Calculates the difference between the two integrated outputs, drives the stage in the Z direction so that the value becomes zero, changes the distance of the slide glass with respect to the objective lens 2 (hereinafter referred to as “objective distance”), and adjusts the focus position.

FIG. 12 shows how the outputs a and b of the integration output by the integration circuits 12 and 13 change with respect to the objective distance d.

In the figure, d _F is a focus position, output level a of the integrator output by each integrating circuit 12, 13, b is consistent, the difference is zero. In the figure, curve 18 indicated by a broken line, the output level a, shows the difference between b (a-b), there is in-focus position d _F in a direction to reduce the object distance d if a-b> 0 And ab <0
Focus position d _F is present in a direction to increase the object distance d long.

In the above configuration, first, a slide glass to be observed is placed and fixed on a stage, and then a focus position is obtained by the focus detection circuit 17 using a frost portion of the slide glass, and a focus operation is performed. The stage is moved in the XY axis direction with respect to the system 1 and scanning is performed. When an object to be observed (hereinafter referred to as “object to be observed”) is detected, the focus is adjusted again at that position to observe the object to be observed. Is what you do.

<Problems to be Solved by the Invention> However, in the case of such a focus adjustment method, when the appearance of the object to be observed on the slide glass is small, if the stage is tilted or the slide glass is distorted, scanning is performed. In addition, there is a problem that the optical system 1 is displaced from the in-focus position, and the object to be observed cannot be detected.

The present invention has been made in view of the above-mentioned problem, and has a small number of appearance of an object to be observed, and a microscope capable of detecting an object to be observed even when the stage is tilted or the slide glass is distorted. It is an object of the present invention to provide an automatic focusing device.

<Means for Solving the Problems> The present invention relates to an automatic focus adjustment device for automatically adjusting the focus of an optical system in a microscope, and an observation means for enlarging and observing a part of an observation target with an optical system. Focusing means for processing an observation signal from the observation means to detect a focus position of the optical system to perform a focusing operation; scanning means for relatively moving the optical system to an object to be scanned for scanning; Object detection means for detecting a focus-adjustable object based on an observation signal from the means and outputting a detection signal; counting means for counting the number of times of focusing for each predetermined scanning range; and detection operation by the object detection means. Control means for causing the focus adjustment means to execute a focusing operation in response thereto, and prohibiting the focusing operation when the count value of the counting means reaches a set value.

<Operation> Each time the object detection unit detects an object whose focus can be adjusted, the focus adjustment unit automatically performs a focusing operation each time, so that the focus shift caused by the tilt of the stage or the distortion of the slide glass may occur. Even if it occurs, it is corrected as much as possible, so that the object desired to be observed can be detected. In addition, when the number of times of focusing reaches a set value in a predetermined scanning range, the focusing operation is prohibited. Therefore, even if there are many objects that can be adjusted in focus, the observation work is delayed due to frequent focusing operations. Can be prevented, and smooth observation can be realized.

<Embodiment> Fig. 1 shows the overall configuration of an automatic focus adjusting device for a microscope according to an embodiment of the present invention, and includes an observation unit 38, a focus detection circuit 32, a Z-axis driving unit 33, and an XY-axis driving unit. 34, a motor controller 35, an object detection circuit 36, a CPU 37, and the like.

The observation unit 38 includes an optical system 21 having a configuration as shown in FIG.
, A stage 22, and two CCD line sensors 30, 31.

The stage 22 is configured to be movable in each direction of XYZ, and a slide glass 23 to be observed can be fixed on an upper surface thereof. The drive of the stage 22 in the Z-axis direction is Z
The axis driving unit 33 is responsible for driving in the XY axis direction by the XY axis driving unit 34. The focus adjustment is performed by driving the stage 22 in the Z axis direction, and the stage 22 is driven in the XY axis direction. Accordingly, the scanning of the slide glass 23 by the observation unit 38 is realized. A light source 24 for illumination is located behind the stage 22, and an objective lens 25 of the optical system 21 is located directly above.

The optical system 21 includes two beam splitters 26 and 27, and CCD line sensors 30 and 31 are respectively arranged on two optical paths 28 and 29 having different optical path lengths. In the figure, the broken lines indicate the in-focus position of each of the CCD line sensors 30, 31, and one of the CCD line sensors 30 is located at a position separated by a distance -l from the in-focus position.
The other CCD line sensor 31 is disposed at a position apart from the in-focus position by a distance + l and perpendicular to the optical axis. In the drawing, reference numeral 39 denotes an eyepiece.

A video signal of an image obtained by each of the CCD line sensors 30 and 31 is supplied to a focus detection circuit 32, and one CCD line sensor 30
The video signal obtained in is also supplied to the object detection circuit 36. Note that the focus detection circuit 32 has the same circuit configuration as the conventional example shown in FIG. 10, and a description thereof will be omitted.

FIG. 3 shows only a time chart of the object detection circuit 36. The object detection circuit 36 has a gate circuit that allows the video signal A from the CCD line sensor 30 to pass through a gate signal having a pulse width T, and a video signal A that has passed through the gate circuit. A differentiating circuit, a comparing circuit that outputs an object detection signal S to the CPU 37 when the differential output B of the differentiating circuit exceeds a predetermined threshold value TH, and a count value of an internal counter n of the CPU 37 to be described later is a predetermined value. A gate circuit for regulating the output of the object detection signal S when the set value is reached.

When the object detection signal S is input from the object detection circuit 36, the CPU 37 causes the focus detection circuit 32 to execute the detection of the in-focus point, and controls the driving of the Z-axis drive unit 33 via the motor controller 35, thereby controlling the stage 22. Is moved in the Z-axis direction to execute a focusing operation.

Further, the CPU 37 controls the driving of the XY-axis driving unit 34 via the motor controller 35 to move the stage 22 in the XY-axis direction, thereby causing the observation system 38 to scan the slide glass 23.

FIG. 4 specifically shows a configuration of the slide glass 23 and a scanning method thereof.

The slide glass 23 includes an observation area 42 and a frost portion 41 on which characters and the like are written.
Are scanned by the observation unit 38, and the detection and observation of the observation desired object are executed.

This observation area 42 is partitioned into a plurality of rectangular blocks 43 during scanning. In each block 43, the width L in the X direction is determined according to the field of view of the optical system 21, that is, the length of the CCD line sensors 30, 31, and the width H in the Y direction is set to an arbitrary predetermined value.

In the figure, a broken arrow 44 indicates the scanning order of each block 43. After the stage 22 is moved along the Y direction to scan the first row of each block 43, the stage 22 is moved along the X direction. Each block 43 in the next row is moved by the width L.
Is scanned in the opposite direction to that described above, and the scanning proceeds in the same manner.

FIG. 5 shows a control procedure of the focus adjustment by the CPU 37 for each block 43.

In step 1 (shown as “ST1” in the figure) of FIG.
After clearing the internal counter n that counts the number of times of focusing, the PU 37 drives the XY drive unit 34 via the motor controller 35 and shifts the stage 22 to start scanning by the observation unit 38 for the target block 43. Let it.

When the object detection circuit 36 detects an object whose focus can be adjusted at a certain scanning position and outputs an object detection signal to the CPU 37, step 2 becomes "YES", and the CPU 37 temporarily stores the current scanning position as the in-focus position. After that, in the next step 3, it is determined whether or not this in-focus position is apart from the previous in-focus position by the set distance K.

Figure 7 is an illustration to enlarge the block 43 in the current scan, in the figure, P ₁ to P ₄ indicates the scanning position of the CCD line sensor 30. The figure shows cells, 46 is a nucleus, 47 is a blood cell, and 48 is a dividing object to be observed.

Now the previous focus position is P _1, time, when the position to be executed the focus adjustment is to be P _2, the distance y ₁ between them from the smaller set distance K, the determination in Step 3 The result is "NO", the focusing operation from step 4 on is skipped, and the stored content of the current focusing position data is cleared. The time, when the position to be executed the focus adjustment is to be P _3, the distance y ₂ therebetween proceeds from a larger set distance K, to step 4 becomes the determination of Step 3 is "YES", CPU 37 Controls the focus detection circuit 32 to perform focus detection, and controls the drive of the Z-axis drive unit 33 via the motor controller 35 to move the stage 22 in the Z-axis direction to execute a focusing operation.

As a result, when focusing is performed, step 5 becomes "YES", the content of the counter n is incremented in the next step 6, and whether or not the content of the counter n has reached the set value N in the following step 7 Is determined. If the determination is "NO", the process returns to step 2 via step 9;
The same procedure as described above is performed.

If the determination in step 7 is "YES", the CPU 37 inhibits the output of the object detection signal to the object detection circuit 36, thereby restricting the execution of the focusing operation until the scanning of the block 43 is completed. (Step 8).

In the above procedure, if the scanning of the block 43 is completed while the content of the counter n is zero, there is no object that can be adjusted in the focus in the block 43, or the block 43 is caused by the inclination of the stage 22 or the like. Is out of focus.
The search for the focal point is executed according to the procedure shown in the figure.

FIG. 8 shows a state in which the focusing operation is performed at each broken line position of the first block 43a, but the scanning is shifted to the next block 43c without performing the focusing operation in the next block 43b. .

First, at step 10 in FIG. 6, it is determined whether or not the content of the counter n is zero. In the example of FIG. 8, since the determination in step 10 is "YES", the process proceeds to step 11, in which the CPU 37 drives the Z-axis driving unit 33 via the motor controller 35 to set the objective distance within a predetermined range within a predetermined pitch. by H ₀ is changed, the object detection circuit 36 at each position is checked whether to detect objects that may focus adjustment, by entering the object detection signal, to detect the focal point to the focus detection circuit 32, Execute the focusing operation.

As a result, if focusing has not been performed, or if focusing has been performed but the number of times of focusing has not yet reached the predetermined number, step 12 is “NO”, and the CPU 37 transmits the After driving the XY axis driving unit 34 to shift the scanning position from Q ₀ to Q _{1 in} FIG. 8 by a predetermined pitch Y ₀ ,
Similarly to the above, by changing the object distance within a certain range by a predetermined pitch H ₀ to execute the detection and focusing operation of possible objects of the focus adjustment.

Thus, if the number of times of focusing has reached the predetermined number, step 12 becomes “YES”, or if the transition distance for each pitch Y ₀ has reached the predetermined distance R, step 13 becomes “YES”,
After returning the scanning position to the first position Q ₀ of the block 43C, again it starts normal scanning (step 14).

<Effect of the Invention> As described above, according to the present invention, when the object detection means detects an observation object whose focus can be adjusted, the focus adjustment means automatically performs a focusing operation each time, so that the tilt of the stage and the Even if the focus shift occurs due to the distortion of the slide glass, it can be corrected as much as possible, and the object desired to be observed can be detected. In addition, when the number of times of focusing has reached a set value in a predetermined scanning range, the focusing operation is prohibited. Therefore, even if there are a large number of objects whose focus can be adjusted, the observation work is delayed due to frequent focusing operations. This is effective in that the observation can be performed and smooth observation can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the configuration of an observation unit, FIG. 3 is a time chart showing the operation of an object detection circuit, and FIG. FIG. 5 and FIG. 6 are flowcharts showing a procedure of focus adjustment, FIG. 7 is an explanatory diagram showing a block being scanned in an enlarged manner, and FIG. FIG. 9 is an explanatory view showing an execution state of focus adjustment of FIG.
FIG. 10 is an explanatory view showing the optical system of the microscope. FIG. 10 is a block diagram showing the configuration of the focus detection circuit. FIG. 11 is a time chart showing the operation of the focus detection circuit. FIG. 21 ... Optical system, 22 ... Stage 30,31 ... CCD line sensor 32 ... Focus detection circuit, 33 ... Z axis drive unit 34 ... XY axis drive unit 35 ... Motor controller 36 ... Object detection circuit, 37 ... CPU 38 ... Observation unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 7/28 G03B 3/00

Claims (1)

(57) [Claims] An automatic focus adjustment device for automatically adjusting the focus of an optical system in a microscope, comprising: an observation unit for enlarging and observing a part of an object to be observed by an optical system; and an observation signal from the observation unit. Focus adjusting means for detecting a focus position of the optical system to perform focusing operation; scanning means for moving the optical system relative to an object to be scanned for scanning; and focus adjusting based on an observation signal from the observation means. Object detecting means for detecting an object capable of detecting, counting means for counting the number of times of focusing for each predetermined scanning range, focusing operation by the focus adjusting means in response to the detecting operation by the object detecting means, and counting An automatic focus adjusting device for a microscope, comprising: a control unit for prohibiting the focusing operation when a count value of the unit reaches a set value.