JPH0587804B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic focusing method for a microscope.

The conventional automatic focusing method for microscopes was to move the motorized stage over almost the entire movable range and move the motorized stage to the in-focus position based on image information obtained from the image sensor. However, there was a problem that the focusing operation time was extremely long.

In view of the above problems, the present invention provides an automatic focusing method for a microscope in which a motorized stage is moved to a focusing position based on image information obtained from an image sensor. The top surface position of the stage corresponding to the theoretical focus of the slide glass corresponding to the thickness is set as the focus position, and a position slightly further from the focus position than the objective lens is set as the reference position of the stage. A position detection means is provided for detecting the positional state of the stage from the reference position, and when image information is obtained at the initial position of the stage at the time of starting focusing, a focusing operation is performed based on the image information obtained there. , if image information cannot be obtained at the initial position of the stage, the stage is temporarily moved to the reference position based on the detection signal of the position detection means, and a focusing operation is performed at this reference position based on the image; When image information cannot be obtained at the reference position of the stage,
By moving the stage by a distance of the image information detectable range determined by the objective lens to a position where image information can be obtained, and performing a focusing operation based on the image information obtained there,
The purpose is to provide an automatic focusing method that can significantly shorten the focusing operation time.
The figure shows the optical system of a microscope using this method, where 1 is a light source, 2 is a condenser lens, 3 is a field stop, 4 is an aperture stop, 5 is a condenser lens, and 6
1 is a motorized stage, 7 is a sample placed on the motorized stage 6, 9 is an objective lens, 10 is a beam splitter, 11 is an eyepiece lens, 12 is a photographing lens,
13 is an imaging lens, and 14 is an image sensor, and the image sensor 14 is arranged at a position optically conjugate with the image formation surface formed by the eyepiece lens 11. 2 and 3 are horizontal and vertical cross-sectional views showing the specific structure of the electric stage 6, in which 15 is a stage;
16 is a stage receiver that instructs stage 15, 1
Reference numeral 7 denotes a movable member to which a stage support 16 is fixed, and the movable member 17 is guided so as to be movable up and down by a guide 19 provided on the microscope body 18, and a stopper 2 fixed to the microscope body 18.
0 restricts its vertical movement range. 21
22 is a pinion that meshes with the rack 21; 23 is a fine movement shaft having a manual knob 24 and a gear 25 fixed to one end; its rotation is decelerated by a planetary gear (not shown); The signal is transmitted to the pinion 22. 26 is a gear meshing with the gear 25; 27 is a drive motor connected to the gear 26 via a clutch 28; in the case of manual operation, that is, the manual knob 2;
4, the clutch 28 is disengaged so that the rotation of the motor 27 is not transmitted to the gear 26, and when the motor is operated electrically, the clutch 22 is engaged and the rotation of the motor 27 is transmitted to the gear 21. 2
9 is a detection plate fixed to the movable member 17; 30, 3;
Reference numeral 1 denotes a sensor such as a photo sensor that is adjustable in the vertical position of the microscope main body 18 in order to detect the position of the detection plate 29. FIG. 4 shows a preset reference position S that is almost equal to the logical focus position determined by the optical system, a mechanical upper limit position A and a lower limit position B, and an upper limit position C and a lower limit position D by the sensors 30 and 31. 32 is a slide glass placed on the stage 15, 33 is a cover glass, and 34 is an objective lens of the microscope. Here, the reference position S is the maximum allowable thickness of the slide glass (1 mm) 32 used.
This is the position of the top surface of the stage 15 when in focus using a slide glass for reference adjustment thicker than 1.5 mm (approximately 2 mm), and other positions A, B,
C and D also indicate the position of the upper surface of the stage 15. Further, the upper limit position C and the lower limit position D determined by the sensors 30 and 31 are selected to be, for example, 0.2 mm inside the mechanical upper limit position A and the lower limit position B, respectively.
FIG. 5 shows a change in the positional relationship between the detection plate 29 and the sensors 30, 31, that is, a change in the position of the stage 15. Here, the height of the detection plate 29 is selected to be c+d, and the detection position of the sensors 30, 31 is The interval between is d
It has been precisely adjusted to (1) shows a state in which the sensors 30 and 31 are at the upper limit position C, and at this time the outputs of the sensors 30 and 31 are 0 and 0, respectively.
It is 1. (2) indicates a state between the upper limit position C and the reference position S, and at this time the outputs of the sensors 30 and 31 are both 0. (3) indicates a state at the reference position, and (4) indicates a state between the reference position S and the lower limit position D determined by the sensors 30 and 31; in both cases, the outputs of the sensors 30 and 31 are Husband 1,
It is 0. (5) indicates a state at the lower limit position D, and at this time the outputs of the sensors 30 and 31 are both 1.

Next, an automatic focusing method according to the present invention using the above device will be explained. In the present invention, the reference position S of the stage 15 is set to be the position of the upper surface of the stage 15 when a 2 mm thick slide glass for reference adjustment is used to bring the image into focus. Generally, the thickness of the slide glass 32 is around 1 mm, and the maximum allowable thickness is 1.5 mm, so when actually examining a sample, the stage 15 is often located above the reference position S. That is, stage 15
The reference position is set at a position slightly further away from the lens from the focus position of the stage 15 corresponding to the focus position of the slide glass 32 corresponding to the maximum allowable thickness of 1.5 mm. Further, in the initial state of the speculum, the position of the stage 15 is generally either above or below the reference position S.

First, if the stage 15 is above the reference position S, there is a possibility that the image sensor 14 is capturing image information of the sample, and in that case, it is necessary to move the stage 15 to the reference position to capture the image information. Therefore, the stage 15 can be quickly moved to the focused position and stopped by immediately performing a focusing operation based on the image information. If image information cannot be obtained even when the stage 15 is above the reference position S, the stage 15 is momentarily lowered by a predetermined distance from the reference position S based on the detection signals of the sensors 30 and 31. After that, the stage 15 is raised again, and the moment the sensors 30 and 31 detect that the stage 15 has reached the reference position S as shown in FIG. 5, the stage 15 is stopped. If image information is obtained at this reference position, the stage 15 can be slightly moved toward the side of the objective lens 9, and a focusing operation can be quickly performed based on the image information. If the objective lens has a high magnification and image information cannot be obtained even at this reference position, the image information detectable range determined by the objective lens (the depth of focus plus the blurred image detection range located on both sides) The stage 15 is raised step by step by a distance of In this way, image information can be captured in a short time, and a focusing operation can be performed based on this image information. If the stage 15 is below the reference position, the stage 15 may be raised a predetermined distance above the reference position S, and then the same operation as described above may be performed.

As described above, according to the automatic focusing method for a microscope according to the present invention, the reference position is set in advance and the stage is moved to the reference position based on the detection signal from the position detection means. It is no longer necessary to move the lens over the entire movable range, and the focusing operation time can be significantly shortened. This method also has the advantage that it can be applied to any objective lens and is highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the optical system of a microscope using an embodiment of the automatic focusing method according to the present invention, and FIGS. 2 and 3 are horizontal sectional views showing the specific structure of the motorized stage of the microscope, respectively. A vertical sectional view, FIG. 4 is a diagram showing the relative positional relationship between the reference position, the mechanical upper and lower limit positions, and the upper and lower limit positions by the sensor, and FIG. 5 is a diagram showing changes in the positional relationship between the detection plate and the sensor. It is. 6...Electric stage, 14...Image sensor, 15
... Stage, 29 ... Detection plate, 30, 31 ...
Sensor, 32...Slide glass.

Claims (1)

[Claims] 1. In an automatic focusing method for a microscope in which a motorized stage is moved to a focusing position based on image information obtained from an image sensor, The top surface position of the stage corresponding to the theoretical focus of the corresponding slide glass is set as the focus position, and a position further away from the focus position from the objective lens is set as the reference position of the stage, and the reference set in advance is set as the reference position of the stage. A position detection means is provided to detect the positional state of the stage from the position, and if image information is obtained at the initial position of the stage at the time of starting focusing, the focusing operation is performed based on the image information obtained there, and the position of the stage is If image information cannot be obtained at the initial position, the stage is temporarily moved to the reference position based on the detection signal of the position detection means, and if image information can be obtained at this reference position, the image information obtained there is When image information cannot be obtained at the reference position of the stage, the stage is moved by a distance of the image information detectable range determined by the objective lens to a position where image information can be obtained. An automatic focusing method for a microscope that performs focusing operations based on the image information obtained.