JP2002072099A - Focusing device for microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and rapidly carry out work for focusing with a focusing device for a microscope. SOLUTION: This focusing device includes a driving means 13 for driving a stage 1 or an objective lens 8 in order to regulate the distance between the stage 1 and the objective lens 8, a specimen position detecting means 11 for detecting the position of the specimen in its optical axis direction with respect to its focal position, a driving speed setting means 14 for setting the driving speed of the stage 1 or the objective lens 8 in accordance with the signal intensity from the specimen position detecting means 11 and a control means 12 for controlling the driving by the driving means 13 and having the driving of the stage 1 or the objective lens 8 executed in correspondence to the driving speed set by the driving speed setting means 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focusing device used for focusing an observation sample on a microscope.

[0002]

2. Description of the Related Art Conventionally, as a focusing device used for focusing an observation sample in a microscope, a stage on which a sample is mounted or an objective lens is moved up and down by manual operation using a combination of a rack and a pinion. A device that performs focusing and a device that performs focusing by an electric operation that causes the drive of the rack and the pinion to interlock with an actuator such as a stepping motor are used.

The automatic focusing device described in Japanese Patent Publication No. 63-56961 and Japanese Patent Publication No. 5-87804 has an automatic focusing operation (autofocus, hereinafter referred to as AF).
In the former, the driving speed is changed depending on whether the taking lens is within a predetermined range near the focal point in the control during the AF operation, and the latter is the latter. When the image information for focus detection cannot be obtained at the start of focusing, the stage is moved in advance to a reference position near the focus position, and then the focusing operation is restarted. . According to these focusing devices, focusing can be performed quickly and skillfully.

[0004] However, since the above focusing devices are all assumed to be added to the AF function, that is, they are used only during the AF operation.
For example, in the case where focusing becomes impossible due to the reflectance or image information of the observation sample, etc., focusing with the AF function removed is still performed.
It is necessary to switch the coarse / fine movement switch to approach to the vicinity of the in-focus position and fine-adjust the focus in the vicinity of the in-focus position. Therefore, the camera may pass through the focus position in the coarse movement state. However, it takes time to focus.

Further, in a general microscope, when exchanging a specimen or exchanging an objective lens, in order to prevent destruction of the specimen due to collision between the specimen and the objective lens, once the distance between the stage and the objective lens is sufficiently increased, the specimen is temporarily separated. After the replacement and the replacement of the objective lens, the lens is returned to the original position again. However, in the focusing device described in the above publication, optimization of the efficiency spent on the driving operation in such a case is not considered. For example, a stage retreat switch or the like is separately prepared, and High-speed evacuation / recovery is being performed. For this reason, the coarse / fine switch and the stage retreat switch must be handled, and at present, efficient work cannot be expected.

On the other hand, the focusing mechanism of the microscope described in Japanese Patent Application Laid-Open No. 9-213335 is provided with a position detection sensor near the in-focus position, and the range detected by this sensor, that is, the in-focus position By changing the moving speed of the driving means between the vicinity and the range not detected by this sensor, that is, outside the range near the focusing position, switching of coarse / fine movement can be realized by only a single operation, and for sample exchange and objective lens exchange. This makes it possible to reduce the time spent.

However, in a normal microscope, various objective lenses having different magnifications are mounted.
Depending on the type, the distance (WD) from the focus position to the objective lens and the manner of blurring the image greatly differ. For example, 1
The high magnification objective lens of 00 times has an extremely small WD compared to the low magnification objective lens of about 5 times, and the blur of the sample is sharp. In other words, the higher the magnification of the objective lens, the narrower the fine movement range near the focusing position in the driving means. A device such as adjustment is required.

However, in the focusing mechanism of the above-mentioned microscope, the physical length (range) of the position detection sensor depends on
The fine movement range of the driving means could not be changed depending on the type of the objective lens. For this reason, when the fine movement range is set at a sufficient distance from the focus position in correspondence with the low-magnification objective lens, the Z of the driving means is adjusted in accordance with the resolution of the high-magnification objective lens.
If the amount of movement (in the direction of the optical axis) is set small, there is a problem that it takes time to focus. Therefore, if the Z (optical axis direction) movement amount of the driving means is set to be large in order to increase the speed, there is a problem in that the resolution at high magnification is impaired, and accurate focusing becomes difficult. Furthermore, if the position detection sensor is fixed, it is not possible to set an optimal fine movement range according to the thickness of the specimen and the objective lens.

A microscope focusing device which solves this problem is described in Japanese Patent Application Laid-Open No. 2000-98256. In the focusing device of the microscope described above, by pressing the setting switch at the focus position of the sample, a configuration is adopted in which the stage or the revolver is driven by finely moving a predetermined range from the focus position and coarsely moving outside the range. Thus, short-time focusing is realized with a single operation without performing coarse / fine movement switching. In addition, after the AF function is combined and AF is once focused, coarse /
Since the configuration for automatically setting the fine movement range is also described, it is possible to save the trouble of initial setting by the setting switch.

[0010]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open
In the focusing apparatus for a microscope described in Japanese Patent Application Laid-Open No. 000-98256, initial setting can be omitted when an AF function is added, and a microscope without an AF function, or focusing cannot be performed. AF
For focusing in a state where the function is removed, setting of the coarse / fine movement range by the setting switch is indispensable.

Further, since the AF device is complicated and finely adjusted, and the microscope mounted with the AF device becomes expensive,
At present, it is difficult to provide an efficient manual focusing function at low cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a microscope focusing apparatus which can efficiently perform a focusing operation in a short time.

[0013]

According to the first aspect of the present invention,
In a focusing device of a microscope that performs focusing by adjusting the distance between the stage on which the sample is mounted and the objective lens,
Driving means for driving the stage or the objective lens to adjust the distance between the stage and the objective lens; sample position detecting means for detecting a position of the sample in the optical axis direction with respect to a focus position; A drive speed setting means for setting a drive speed of the stage or the objective lens based on a signal strength from the position detection means; and a drive speed set by the drive speed setting means, while controlling drive by the drive means. And control means for driving the stage or the objective lens.

According to a second aspect of the present invention, the driving speed setting means sets a driving speed of the stage or the objective lens based on a signal intensity from the sample position detecting means and a driving direction of the driving means. It is characterized by the following.

According to a third aspect of the present invention, the driving speed setting means is configured to control the stage or the objective lens based on a signal intensity and a change amount of the signal from the sample position detecting means and a driving direction of the driving means. The driving speed is set.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a schematic configuration of a microscope focusing apparatus to which the first embodiment according to the present invention is applied. In the figure, reference numeral 1 denotes a stage on which a sample S is mounted. An illumination optical system 201 is provided below the stage 1. This illumination optical system 20
1 is provided with a light source 2 for illuminating the sample S, and illuminating light from the light source 2 is collected by a collector lens 3 and an ND for light control
The light enters the mirror 6 via the filter 4 and the field stop 5, and the illumination light reflected by the mirror 6 is applied to the sample S via the condenser lens 7.

On the other hand, an observation optical system 8 is provided above the stage 1.
01 is arranged. The observation optical system 801 allows the light beam transmitted through the sample S to pass through the objective lens 8 attached to the revolver 9, and allows the eyepiece 10 to observe the sample. Reference numeral 11 denotes a sample position detection unit having the configuration shown in FIG. That is, in the figure, the laser beam emitted from the light source 20 is converted into a deflecting beam splitter (P
BS) 21, the light is guided to the sample S side via the 1 / 4λ plate 22, and the reflected light from the sample S is reflected by the 1 / 4λ plate 22, the polarizing beam splitter (PBS) 21 and the pinhole 23.
Is transmitted and projected onto a photodiode (PD) 24. When the sample S is at the focus position, the amount of light projected from the pinhole 23 to the photodiode 24 is maximized. Therefore, the position of the sample S in the optical axis direction and the intensity of the signal photoelectrically converted by the photodiode 24 are determined. Figure 3
It becomes as shown in. In FIG. 3, the vertical axis represents the sample position signal intensity, and the horizontal axis represents the position in the stage Z-axis direction.

The sample position detecting unit 11 has a CP
U12 is connected. The CPU 12 includes a revolver 9, a stage driving unit 13, and an external controller 14.
Is connected. The stage driving section 13 drives the stage 1 in the optical axis direction, that is, the Z axis direction. The external controller 14 is operated by an observer, and includes a plurality of switches 15 for exchanging the objective lens 8 and setting the type of the objective lens and a jog for outputting a predetermined pulse signal by a rotation operation. JOG) 16
have.

The CPU 12 includes an external controller 14
Based on the pulse signal from JOG 16 of
A signal for driving the stage 1 in the Z-axis direction is output to the stage driving unit 13. Also, the sample position detection unit 1
The signal level output from the stage 1 is detected, and the signal output to the stage drive unit 13 can be changed accordingly.

Further, the CPU 12 receives the optimum coarse / fine movement speed of the stage 1 corresponding to each objective lens 8 set by the external controller 14 from the mounting objective lens information stored in advance and the revolver 9 from the objective lens mounting. It is determined from the hole information.

The operation of the first embodiment having the above configuration will be described.

When the observer turns on a power switch (not shown), the light source 20 in the sample position detecting unit 11 is turned on, and a laser beam is projected on the sample S. The laser light reflected by the sample S is received by the photodiode 24 in the sample position detection unit 11, is photoelectrically converted, and is always detected by the CPU 12 as a sample position signal.

As shown in FIG. 3, the CPU 12 compares a predetermined value (TH1) set in advance with the detected sample position signal, and adjusts the level of the sample position signal to the predetermined value (TH1).
If it is smaller than 1), it is set to "coarse movement mode", and conversely, if the level of the sample position signal is larger than a predetermined value (TH1), it is set to "fine movement mode". Switching between the above two modes is automatically performed by a sample position signal which is always detected.

From this state, the observer rotates the jog (JOG) 16 arranged in the external controller 14 and sends a pulse signal from the jog (JOG) 16 to the CPU 1.
When input to 2, the CPU 12 counts pulse signals input within a predetermined time. In addition, jog (JOG)
Reference numeral 16 denotes a configuration in which the count increases or decreases depending on the rotation direction.

Then, the CPU 12 sets the number of output signal pulses to the stage drive section 13 corresponding to the count number after a predetermined time to Pout: the number of output pulses to the stage drive section 13, and Pin: within a predetermined time. The number of counted input pulses from the jog (JOG) 16 is calculated as α: a moving speed coefficient as Pout = Pin × α, and output to the stage driving unit 13.

At this time, in the coarse movement mode described above, α
Is large, and if the mode is the fine movement mode, α is small. α
Is determined for each objective lens inserted in the optical path from the mounting objective lens information stored in advance and the objective lens mounting hole information received from the revolver 9.

In the coarse movement mode, α is determined so that the fastest stage drive can be performed within a range in which the sample position signal in the fine movement mode range (range a) in FIG. 3 is not missed. On the other hand, in the fine movement mode, α is set to a stage speed that allows the observer to perform focusing with sufficient accuracy in consideration of the magnification and the depth of focus of each objective lens.

As described above, the stage movement speed automatically changes due to slight movement around the focus position and coarse movement outside the focus position, so that the observer can rotate the jog at the same speed to perform high-speed movement. Both the approach to the vicinity of a proper focus position and the highly accurate focusing can be performed without special setting and switching operation.

When the observer lowers the stage from the focus position at the time of exchanging the sample, the observer moves away from the focus position, and when the sample position signal falls below TH1, the coarse movement is automatically performed. Without performing any special operation, it can be efficiently performed with only a single operation using a jog.

Further, in the vicinity of the focus position, focusing can be performed at an optimum stage moving speed for each objective lens, so that troublesome malfunctions such as passing through the focus position are reduced.

A modification of the embodiment will be described.

In this embodiment, the light source in the sample position detecting unit is a laser beam. However, the same effect can be obtained by using a laser beam as the light source. The same effect can be realized by using an optical path splitting element such as a half mirror instead of the PBS.

Further, as for the position detection method of the sample position detection unit, it is sufficient that the above-described sample position signal can be detected. For example, an active method of blocking half of the projected light and detecting the state of the reflected light incident on the light receiving element. Even if it is replaced with a well-known sample position detection method such as the knife edge method or a passive contrast method that uses a CCD line sensor as a light receiving element and obtains the total contrast of the sample image, as shown in FIG. Since the sample position signal can be detected, the same effect as in the present embodiment can be achieved.

A second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the case of microscopic observation, destruction of a specimen due to collision with an objective lens greatly reduces inspection efficiency. One of the causes of collision between the objective lens and the specimen is considered to be that the stage is raised significantly from the focus position of the specimen, and this is often seen particularly in high magnification objective lenses with a small WD.

Destruction of the specimen due to the above-mentioned causes can often be avoided in advance by visual observation or the like if the stage movement time from the specimen focus position to collision with the objective lens is long.

The present embodiment has been made with a focus on the above-mentioned avoidance plan. Usually, the stage is moved at a high speed below the sample focus position when the stage is retracted, but the sample focus position is not changed. There is no need to move the stage at a higher speed than above. Therefore, the stage drive is slowed down in the range above the focus position of the specimen, microscopic observation,
It is intended to improve the inspection.

The difference from the first embodiment is that the CPU 1
2 is a coarse / fine mode switching method.

This will be described with reference to the flowchart of FIG. In order for the observer to focus on the sample S, the jog (JOG) 16 is rotated to drive the stage 1 (step S1), and the sample position detection unit 11 detects a sample position signal from the sample (step S1). S2). It is determined whether or not the level of the sample position signal is equal to or higher than TH1. If the level is equal to or higher than TH1, the stage 1 is driven at a low speed via the stage driving unit 13 in the fine movement mode (step S3). When the driving direction of the stage 1 is lower than TH1, it is determined whether or not the driving direction of the stage 1 is upward. When the driving direction of the stage 1 is upper, the stage driving is not performed in the fine motion mode without switching to the coarse motion mode. Through the section 13, the low-speed driving of the stage 1 upward is continued. If the driving direction of the stage 1 is not upward, the mode is switched to the coarse movement mode, and the stage 1 is moved downward at a high speed via the stage driving unit 13 (step 4).

The operation of the second embodiment having the above configuration will be described with reference to FIG.

It is assumed that the stage 1 is located at a position Pa near the focus position of the sample S. From this state, in order for the observer to move the stage 1 upward, the external controller 1
The jog (JOG) 16 arranged in 4 is operated to rotate,
A pulse signal from the jog (JOG) 16 is input to the CPU 12 (step S1). As in the first embodiment, the CPU 12 calculates an output pulse to the stage driving unit 13 (Step S2), and drives the stage 1 upward with a slight movement (Step S3).

When the position of the stage 1 is higher than Pb, the sample position detection signal from the sample position detection unit 11 is lower than TH1 (step S3). At this time, the CPU 12 determines that the driving direction of the stage is upward (step S
4) The stage 1 is not set to the coarse movement mode,
Continue moving upwards.

According to the second embodiment, it is not necessary to switch between coarse and fine movement of the stage, and it is possible to efficiently perform focusing and retreating the stage by a single operation. In addition, since the problem of specimen destruction due to collision between the specimen and the objective lens can be reduced, it is possible to prevent a decrease in inspection efficiency due to specimen destruction.

FIG. 1 shows a third embodiment of the present invention.
This will be described with reference to FIGS.

The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In a so-called active-type sample detection method of projecting a light beam for position detection onto the sample, such as the sample position detection unit 11 shown in FIG. 2, the above-described coarse detection is performed based on the intensity of light reflected from the sample, that is, the reflectance of the sample. / The range of fine movement changes.

On the other hand, even when the sample position detection unit 11 is a so-called passive sample position method in which the total contrast of the sample image is detected by, for example, a CCD line sensor or the like, the coarse / high contrast of the sample causes
The fine movement range similarly changes.

FIG. 5 shows a change in the intensity of the sample position signal with respect to the sample position in the optical axis direction, similarly to FIG. In the figure, A is a sample position signal for a sample having low reflectance such as glass, and B is a sample position signal such as a mirror.
This is a sample position signal detected from a sample having a high reflectance.

In order to realize the function of the focusing device described in the first and second embodiments using the active-type sample position detecting method irrespective of the reflectance of the sample, coarse / fine movement The switching point TH1 needs to be set lower than the peak value of the sample position signal A in the low reflectance sample. This is because if the value of TH1 is set to be higher than the peak value of A, the fine movement mode is not set at the time of low reflectance sample.

Since the value of TH1 is a fixed value for the same objective lens, the fine movement range b of the sample position signal B at the time of high reflectance sampling is much wider than the range a at the time of low reflectance sampling. Become. Therefore, at the time of the high reflectance sample, the CPU 12
In this case, since the stage 1 is finely moved in the range b, low-speed driving is performed over a wide range, and the focusing efficiency is reduced.

The present embodiment avoids the above-mentioned problem, and realizes efficient focusing regardless of the reflectance or contrast of the sample.

The difference from the first and second embodiments is that C
This is a coarse / fine movement mode switching method in the PU 12. That is, the CPU 12 according to the present embodiment performs the coarse / fine movement determination (hereinafter, referred to as first determination means) by comparing TH1 with the sample position detection signal level described in the first embodiment, and the second determination. It has the fine movement mode fixed drive of the stage above the focus position of the sample S described in the embodiment, and the second determination means described below.

Next, the second judging means will be described. When the stage 1 is moved by L, the signal level change amount is calculated from the sample position detection signal level Sn-1 before movement stored in the CPU 12 and the sample position detection signal level Sn detected after movement by the following equation. Calculate the absolute value β.

Β = | Sn−Sn−1 | / L Then, if the value of β is larger than the threshold value TH2 set in advance, the CPU 12 determines that “coarse movement mode”, and the value of β is larger than TH2. If it is smaller, the mode is set to “fine movement mode”.

Then, the CPU 12 performs a final coarse / fine movement mode determination by a logical product of the result obtained by the above-described second determination means and the result obtained by the first determination means, and (JOG) The stage 1 corresponding to the number of input pulses from 16 is driven.

The operation of the focusing apparatus according to the third embodiment will be described with reference to FIG. 5. The sample S is a sample having a low reflectance, and the sample position detection signal has the characteristic shown in FIG. And In order for the observer to move the stage 1 upward from the position P1 of the stage 1, the external controller 1
When the jog (JOG) 16 arranged in 4 is rotated,
The CPU 12 determines the coarse / fine movement mode based on the first determining means and the second determining means.

In this case, the first judging means determines that TH
The stage 1 is moved in accordance with the rotation of the jog (JOG) 16 in the fine movement mode to a range a above P2 and below P3, which is 1 or more. Also, range a
In this case, the “fine movement mode” is set because β calculated by the second determination means, that is, the change amount of the sample position detection signal is equal to or less than TH2. Therefore, the logical product of the results of the first and second determination means is in the “fine movement mode”, and the CPU 12
The stage 1 is driven by the fine movement via the stage driving unit 13.

Next, it is assumed that the sample S is a sample having a high reflectance, and the sample position detection signal has the characteristic shown in B in the figure.

When the observer rotates the jog (JOG) 16 disposed in the external controller 14 to move the stage 1 upward from the position of the stage 1 at the position P4, the CPU 12 determines the first discriminating means. The coarse / fine movement mode is determined based on the second determination means.

That is, in the range b in the figure, the sample position detection signal level is higher than TH1, so that the first determination means is in the "fine movement mode", but the β calculated by the second determination means, ie, the sample position The change amount of the detection signal is TH2
Because of the above, the “coarse movement mode” is determined, and the first,
The logical product of the result of the second determination means becomes the “coarse movement mode”, and the CPU 12 drives the stage 1 through the coarse movement via the stage drive unit 13.

Further, when the sample position detection signal level is TH1
The stage 1 is driven by the coarse movement until the position of P5 at which the value of β of the second determination means becomes equal to or less than TH2.

In the figure, the value of β calculated by the second judging means exceeds TH2 up to the focus position beyond P5.
(The range of c in the figure), the mode becomes the "fine movement mode", and the logical product of the results of the first determination means and the second determination means becomes the "fine movement mode".

The coarse / fine movement mode is determined in the same procedure for the direction away from the focus position.

However, for driving the stage 1 upward from the focus position, the stage 1 is slightly moved irrespective of the results of the first and second determination means, as in the second embodiment. Drive.

According to the third embodiment, an unnecessary fine movement range is not widened even for a sample having a high reflectance or a sample having a high contrast. Focusing and retraction of the stage can be performed.

In the first to third embodiments, the adjustment of the distance between the specimen and the objective lens has been described by the stage drive. However, for example, a method in which the revolver on which the objective lens is mounted is driven up and down is changed. However, exactly the same effect can be obtained.

Although a dedicated optical system is used as a means for detecting the sample position, a microscope equipped with an AF function can determine the coarse / fine movement mode based on a signal from the AF device. There is no need to add an optical system.

The coarse / fine movement speed of the stage is set to a predetermined value for each objective lens set by the external controller. For example, when it is desired to change the coarse / fine movement speed, A predetermined value set in advance is multiplied by n or 1 / n according to an instruction from the controller.
It can be easily realized by adding a configuration that can be multiplied.

Further, by using the sample position detection signal detected by the optical system according to the present embodiment, it is possible to achieve a so-called focus aid function, for example, informing an observer that the subject is near the focus position. is there.

[0071]

According to the present invention, a focusing operation can be efficiently performed in a short time in a focusing device for a microscope.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a focusing device of a microscope according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a sample position detection unit according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a sample position signal intensity according to the first embodiment of the present invention.

FIG. 4 is a flowchart of a second embodiment of the present invention.

FIG. 5 is a diagram showing a sample position detection signal intensity according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Stage 8 ... Objective lens 11 ... Sample position detection unit 12 ... CPU 13 ... Stage drive part 14 ... External controller 16 ... Jog

Claims (3)

[Claims] In a focusing device of a microscope for adjusting a distance between a stage on which a specimen is mounted and an objective lens to perform focusing, the distance between the stage and the objective lens is adjusted. Driving means for driving the stage or the objective lens, sample position detecting means for detecting a position of the sample in the optical axis direction with respect to the focus position, and the stage or the objective based on a signal intensity from the sample position detecting means. Driving speed setting means for setting the driving speed of the lens; controlling the driving by the driving means; and driving the stage or the objective lens in accordance with the driving speed set by the driving speed setting means. A focusing device for a microscope, comprising: a control unit. 2. The apparatus according to claim 1, wherein said driving speed setting means sets a driving speed of said stage or said objective lens based on a signal intensity from said sample position detecting means and a driving direction of said driving means. Item 7. A focusing device for a microscope according to Item 1. 3. The drive speed setting means sets a drive speed of the stage or the objective lens based on a signal intensity and a change amount of the signal from the sample position detection means and a drive direction of the drive means. Claim 1 characterized by the following:
A focusing device for the microscope as described.