JP2003315679A - Microscope system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microscope system having an overcontact preventive function capable of detecting the contact of a viewing object and an objective lens with high accuracy and preventing damaging of either or both by the overcontact of both. <P>SOLUTION: The microscope system makes at least either of a stage 2 to be placed on with a specimen 4 and the objective lens 6 relatively in an optical axis direction movable. When the contact of the specimen 4 and the objective lens 6 is detected by a contact detecting sensor 11, a DC component is removed in a contact deciding section 12 for the output according to the contact detection and the contact decision of the specimen 4 and the objective lens 6 is performed in accordance with the output removed of the DC component and at least either of the stage 2 and the objective lens 6 is controlled by the result of the decision. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope system, and more particularly to a microscope system having a function of preventing an observation object and an objective lens from making excessive contact.

[0002]

2. Description of the Related Art Recently, an object to be observed, that is, an object to be inspected, has to be observed at a high magnification for inspection of miniaturized IC wiring and the like in the industrial field and inspection of cell nucleus in the medical field. Many possible microscopes are being used.

By the way, in order to observe an object to be inspected at a high magnification using such a microscope and obtain an observation image of the object to be inspected at a high resolution, it is avoided to use an objective lens having a high NA. It is said that it cannot be done. However, high NA
The more the objective lens having is used, the closer the observation observation object and the objective lens are to each other. For example, N
In the case of an objective lens with A = 0.9 and a magnification of 100, the distance between the observation object and the objective lens, so-called W. D (Working
Distance) is 200 [μm].

However, as described above, the W. When D becomes short, contact between the observation object and the objective lens easily occurs. In particular, the object to be observed is a finely divided I as described above.
In the case of a C wiring or a very fine one such as a cell nucleus, the observation object may be damaged by the contact of the objective lens with the observation object. Further, when the observation object is a hard object such as metal, if the objective lens comes into contact with the observation object, the objective lens may be damaged.

Therefore, in order to prevent the contact between the object to be observed and the objective lens, various over-contact preventing systems have been conventionally proposed. For example, in Japanese Unexamined Patent Publication No. 5-26612 and Japanese Unexamined Patent Publication No. 10-260361, a pressure detection sensor or a contact sensor for detecting the contact between an observation object and an objective lens is provided to detect the contact between the observation object and the objective lens. A microscope system for preventing contact is disclosed.

[0006]

Such an over-contact prevention system prevents damage to the observation object or the objective lens in response to contact between the observation object and the objective lens. First, the system is activated to interrupt the operation of the microscope before damage occurs. Therefore, in a system in which a detection sensor is used, it is important that the output from the detection sensor is monitored and that the threshold value for determining contact is as close as possible to the sensor output obtained immediately after contact. This makes it possible to quickly interrupt the microscope operation and minimize the influence on the observation target.

However, since the sensor itself or the circuit for processing the sensor output is affected by the change in ambient temperature, the actual threshold value is set to have a margin. Therefore, depending on how this margin is taken, there is a problem that it cannot be accurately determined that the observation object and the objective lens are in contact with each other. In particular, in a microscope system that uses a transmissive light source that observes an object with a light beam that has passed through a specimen that is an observation object, a sensor is provided close to the observation object, and the transmitted light beam is also incident on this sensor during observation. The temperature of the sensor itself may be slightly changed. The characteristics of the sensor may change due to the temperature change of the sensor, and it may not be possible to accurately determine that the observation object and the objective lens are in contact with each other.

This is true of the microscope system using the pressure detecting sensor disclosed in Japanese Patent Laid-Open No. 5-266612 and the microscope system using the contact sensor disclosed in Japanese Patent Laid-Open No. 10-260361. However, no solution for the above problem is disclosed. Therefore, in the conventional microscope system disclosed in these publications, if the margin for the sensor output is too large, it is determined that the observation object and the objective lens have come into contact with each other due to the output from the sensor, and even if the microscope operation is interrupted, The observation object and the objective lens may already be in contact with each other and damage the observation object. Further, if the margin for the sensor output is small, there is a problem that the microscope operation is interrupted even though the observation object and the objective lens are not in contact with each other, and stable contact cannot be determined.

The present invention has been made in view of the above circumstances, and prevents the contact between the observation object and the objective lens with high accuracy and prevents the two from over-contacting and damaging one or both. An object of the present invention is to provide a microscope system having an over-contact preventing function that can be performed.

[0010]

The invention according to claim 1 is
In a microscope system in which an objective lens for observing the observation target object is relatively movable in the optical axis direction with respect to a stage on which the observation target object is placed, between the observation target object and the objective lens. Detecting the contact state of, detecting means for outputting a detection signal according to the contact state, a DC component removing means for removing a DC component from the detection signal output from the detecting means to generate a contact determination signal, Based on the contact determination signal, a determination unit that determines that the contact state between the observation object and the objective lens exceeds a predetermined value and outputs an overcontact signal, and in response to the overcontact signal, the determination unit It is characterized by comprising a stage and a control means for controlling relative movement of the objective lens.

According to a second aspect of the present invention, a stage on which an observation object is placed, a plurality of objective lenses for observing the observation object, and one objective lens is selected from the plurality of objective lenses. And an objective lens selecting means for arranging the objective lens on the optical axis of the microscope, and a moving means for relatively moving the selected objective lens with respect to the stage at a relative speed depending on the selected objective lens. Provided for each of the objective lenses, detects a contact state between the observation object and the selected objective lens depending on the selection of the objective lens, and outputs a detection signal corresponding to the contact state. A detection element, a filter unit that generates a contact determination signal from which a direct current component is removed from the detection signal, and a contact state between the observation object and the objective lens is predetermined based on the contact determination signal. And a control means for controlling the relative movement of the stage and the objective lens in response to the over-contact signal. .

The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention described above, the direct-current component removing means includes a high-pass filter for removing low-frequency components.

The invention according to claim 4 is the invention according to claim 1 or 2.
In the invention described above, the direct-current component removing means is characterized by including a bandpass filter that removes a frequency band other than a predetermined frequency band by combining a differential gain characteristic, a proportional gain characteristic, and an integral gain characteristic.

The invention according to claim 5 is the invention according to claim 1 or 2.
In the invention described above, the contact determining means includes a contact determining signal from the DC component removing means and a comparator for comparing a preset threshold value.

The invention according to claim 6 is the invention according to claim 1 or 2.
In the invention described above, the detection means includes a pressure sensor that detects a contact pressure corresponding to a contact state between the observation object and the objective lens.

According to a seventh aspect of the invention, in the second aspect of the invention, the filter means is 50 Hz to 10 kHz.
It is characterized in that it includes a band-pass filter that allows the detection signal to pass in the z frequency band and reduces the other signals.

The invention according to claim 8 is the invention according to claim 7, wherein the band-pass filter is 500 Hz to
The feature is that the detection signal is allowed to pass through in the frequency band of 10 kHz and the other signals are reduced.

According to a ninth aspect of the invention, in the seventh aspect of the invention, the bandpass filter is 50 Hz to 1 Hz.
The feature is that the detection signal is allowed to pass in the frequency band of kHz and the other signals are reduced.

According to a tenth aspect of the present invention, in the invention according to the second aspect, if the detection element has a sensitivity of S (V / μm) and the predetermined value is r (V), the band pass is obtained. The filter is characterized by allowing the detection signal to pass in the frequency band of S / 20r Hz to S / r Hz and reducing the other signals.

According to an eleventh aspect of the present invention, in the invention according to the second aspect, the filter means includes a plurality of filters having filter characteristics corresponding to the respective objective lenses, and the detection means is the selected one. It is characterized by including a switching means for selecting one filter corresponding to the objective lens depending on the objective lens and switching and supplying the detection signal to the selected filter.

As a result, according to the present invention, the influence of drift caused by environmental changes (changes in temperature and humidity) and changes over time can be eliminated, and the contact between the observation object and the objective lens can be performed with high accuracy. It is possible to detect and prevent both from over-contacting and damaging one or both.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a microscope system having an overcontact prevention function according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a microscope main body, which has a horizontal base portion 1A and a body portion 1B provided upright with respect to the base portion 1A.
An objective arm 1C parallel to the base 1A is provided at the tip of the body 1B.

The body 2 of the microscope body 1 has a stage 2 on the body 1B.
Is provided so as to be vertically movable along the optical axis direction of the objective lens 6 described later. The stage 2 can be electrically driven in the vertical direction by a stage motor 3. A sample 4 is placed on the stage 2.

The objective arm 1C is provided with an electric revolver 5. The revolver 5 is provided with a plurality of objective lenses 6 facing the sample 4 on the stage 2.
For example, in a high-performance microscope, the revolver 5 is provided with five objective lenses. By rotating the revolver 5, these objective lenses 6 are selectively switched to the optical path, and one objective lens 6 selected by the user is selected.
Are placed on the optical path. Above the objective arm 1C, A
An F (auto focus) unit 7 is provided, and a lens barrel 8 is provided on the AF unit 7. The lens barrel 8 is provided with an eyepiece lens 9.

A transmission light source 10 is provided below the body 1B of the microscope body 1. The illumination light beam from the transmissive light source 10 is incident on the sample 4 from below the stage 2 via an ND filter (not shown), an aperture stop, and a field stop, which are arranged inside the base portion 1A, and is transmitted through the sample 4. The light flux passes through the objective lens 6 and the AF unit 7, and a part of the light flux is guided to the eyepiece lens 9 through the lens barrel 8.

A contact detection sensor 11 for detecting contact between the sample 4 and the objective lens 6 is provided at the tip of the objective lens 6. The contact detection sensor 11 accurately detects a slight contact between the sample 4 and the objective lens 6. In this specification, the contact between the sample 4 and the objective lens 6 means a state where the sample 4 and the objective lens 6 are in contact with each other so as not to damage the sample 4 or the objective lens 6, and the excessive contact between the sample 4 and the objective lens 6 means It means a strong contact such that a pressure is applied to both or a sudden contact where a strong pressure is instantaneously applied to both, and it does not matter whether one of them is damaged as a result of over-contact. Further, the contact detection sensor 11 may be any type of sensor as long as it detects a contact between the sample 4 and the objective lens 6 and generates a predetermined output.

The contact detection sensor 11 is connected to a contact determination unit 12 for determining contact, the objective lens switching mechanism control unit 13 is connected to the objective lens switching mechanism of the revolver 5, and the stage motor 3 is connected to the stage. The control units 14 are connected to each other. A CPU 15 for controlling each unit is connected to the contact determination unit 12, the objective lens switching mechanism control unit 13, and the stage control unit 14. Also, CPU
The AF unit 7 and the user operation unit 16 are connected to 15. The contact detection sensor 11 includes a contact determination unit 12 via a signal line extending inside the objective lens 6, the revolver 5, and the objective arm 1C and a connection mechanism that electrically connects the signal line.
It is connected to the. The signal line and the connection mechanism are disclosed in Japanese Laid-Open Patent Publication 2000-199858. The detailed description of these signal lines and the connection mechanism will be omitted by citing this publication.

The contact determination section 12 outputs a contact signal to the CPU 15 when the contact detection sensor 11 detects the contact between the sample 4 and the objective lens 6 and a predetermined output is detected.

The CPU 15 controls the stage controller 14 based on the default signal from the AF unit 7. That is, in response to the default signal, the stage control unit 14 drives the stage motor 3 to move the stage 2 up and down, change the relative distance between the sample 4 and the objective lens 6, and control the focusing of the objective lens 6. is doing. Further, in response to the default signal, the CPU 15 instructs the objective lens switching mechanism control unit 13 to switch the objective lens so that the predetermined objective lens 6 is arranged on the optical path. In addition, the contact determination unit 12
When the contact between the sample 4 and the objective lens 6 is determined by the CPU, the CPU
15 gives an instruction to avoid excessive contact to the stage controller 14, and responds to this instruction to avoid excessive contact.
Immediately stops the movement control of the stage 2 and regulates the further movement of the sample 4 and the objective lens 6 in the contact direction.

Various instructions are given to the user operation unit 16 by the user. That is, a user operation of the user operation unit 16 instructs the CPU 15 to turn on / off the autofocus operation by the AF unit 7, or switch the objective lens 6.

FIG. 2 shows a schematic block diagram of the contact determination section 12. The contact determination unit 12 includes a detection circuit 12A, a comparator 12B, a D / A converter 12
Filter circuit 12 for removing a DC component from detection signals from C, A / D converter 12F and contact detection sensor 11.
D.

When the contact detection sensor 11 contacts the sample 4, an output is generated from the contact detection sensor 11 depending on the contact, for example, the contact force or pressure. This detection output is supplied to the detection circuit 12A and amplified. The amplified signal from the detection circuit 12A is supplied to the filter circuit 12D.

The filter circuit 12D has a filter having a gain characteristic shown in FIGS. 3A and 3B, and unnecessary frequency components of the detection signal from the detection circuit 12A are cut off to obtain a required frequency. Only the band signal is output.

FIG. 3A shows the gain characteristic of the primary high-pass filter with respect to the frequency f. This Figure 3
As is clear from (a), since the gain of the low frequency component (cutoff frequency of 5 Hz or less) is low, in the filter circuit 12D including the filter having such characteristics, the DC component in the detection signal, that is, the low The frequency components are substantially removed. The cut-off frequency is based on the operating speed of the stage 2 and the detection sensitivity of the contact detection sensor 11 so that not only the DC component but also low-frequency noise such as vibration noise can be cut off. That is, it is desirable that the frequency be obtained and settings be made so that frequencies below that frequency are removed. It should be noted that such a high-pass filter is not limited to the first-order characteristics, but can have similar characteristics even if it has second-order or higher-order characteristics.

FIG. 3B shows the characteristics of the bandpass filter in which the differential gain characteristic Fa, the proportional gain characteristic Fb and the integral gain characteristic Fc are combined. By giving the characteristics of such a bandpass filter to the filter circuit 12D, low frequency components and high frequency components including DC components are removed by the differential gain characteristic Fa, the proportional gain characteristic Fb and the integral gain characteristic Fc.

In the filter circuit 12D including the filter having the gain characteristic shown in FIGS. 3 (a) and 3 (b), the detection signal from the detection circuit 12A is reduced by the first-order high-pass filter shown in FIG. 3 (a). Frequency noise is cut, or DC is applied by the bandpass filter shown in FIG.
Low-frequency noise and high-frequency noise including components are cut, and only a signal in a required frequency band is amplified and output.

The output of the filter circuit 12D is supplied to one input terminal of the comparator 12B. To the other input terminal of the comparator 12B, a threshold voltage obtained by analog-converting the digital data output from the CPU 15 by the D / A converter 12C is supplied. The comparator 12B compares the threshold voltage supplied from the CPU 15 with the output voltage from the filter circuit 12D. When the output voltage from the filter circuit 12D is higher than the threshold voltage, it is determined that the objective lens 6 and the sample 4 are in contact with each other, and the CPU 15 and the stage control unit 14
Then, the contact signal is sent from the comparator 12B.

Here, when the stage 2 is moving, the stage controller 14 temporarily forcibly stops the operation of the stage 2 in response to the contact signal. Further, in response to the contact signal, the CPU 15 outputs a command for returning the stage 2 to the stage control unit 14, and the sample 4 and the objective lens 6 are output.
The stage is avoided so as to provide a sufficient distance between the sample 4 and the objective lens 6 so that no more contact is made.

On the other hand, when the stage 2 is stationary,
Since there is a possibility that the stage 2 has malfunctioned, the stage control unit 14 temporarily forcibly stops the operation of the stage 2 in response to the contact signal. Further, the CPU 15 outputs a command for returning the stage 2 to the stage controller 14 so as to give a sufficient distance between the sample 4 and the objective lens 6 so that the sample 4 and the objective lens 6 do not contact each other anymore. Let the stage avoid.

In such a microscope system, the contact detection sensor 11 is provided at the tip of the objective lens 6, and the movement of the stage 2 causes the tip of the objective lens 6 to come into contact with the sample 4 on the stage 2. It is detected by the detection sensor 11. The detection output from the contact detection sensor 11 is sent to the filter circuit 12D. In this filter circuit 12D, the low-frequency noise including the DC component is cut by the primary high-pass filter shown in FIG. 3A, and the low-frequency noise and the high-frequency noise including the DC component are cut by the band-pass filter shown in FIG. 3B. Is cut,
Only the signal in the required frequency band is amplified and sent to the comparator 12B. In the comparator 12B, the detection signal is compared with the threshold voltage, and it is determined from this comparison result that the objective lens 6 and the sample 4 are in contact with each other.

In this case, in the first-order high-pass filter shown in FIG. 3A, the stage 2 is arranged so as to cut not only DC components but also low-frequency noise such as vibration noise.
The rising frequency of the output of the detection circuit 12A at the time of contact is determined from the operating speed of 1 and the detection sensitivity of the contact detection sensor 11 and is set so as to be able to remove the rising frequency or lower. In addition, in the bandpass filter shown in FIG.
The differential gain characteristic Fa, the proportional gain characteristic Fb, and the integral gain characteristic Fc are set so that the low frequency component and the high frequency component including the DC component can be removed. Therefore, it is possible to eliminate the influence of a slight drift due to environmental changes, for example, changes in temperature or humidity, or changes over time with respect to the contact detection sensor 11 itself and the processing means in the subsequent stage.

As a result, the detection signal is compared with the threshold voltage in the comparator 12B, and the contact between the objective lens 6 and the sample 4 is made with high accuracy based on the comparison result.
It can be detected at high speed. As a result, the objective lens 6
Even if an accident occurs in which the sample 4 and the sample 4 come into contact with each other, the operation of the stage 2 is temporarily forcibly stopped, and the avoidance operation that prevents the sample 4 and the objective lens 6 from contacting each other is performed accurately and promptly. Therefore, it is possible to minimize damage to both the objective lens 6 and the sample 4.

Further, depending on the setting of the threshold value in the comparator 12B, noise components other than the DC component equivalent to the drift component, for example, electrical noise such as power supply noise or mechanical noise such as vibration may occur. A certain malfunction can be prevented, and highly accurate contact determination can be performed.

The filter circuit 12D shown in FIG. 2 includes the high-pass filter shown in FIG. 3A and the band-pass filter shown in FIG. 3B, but may have only one of them.

The characteristics of this bandpass filter may be determined as follows. In the microscope system shown in FIG. 1, five objective lenses 6, for example, 5 ×, 10
The objective lens 6 having a magnification of × 20, × 50, × 100, or × 100 is provided, and a contact detection sensor 11 having the same detection sensitivity is attached to each objective lens 6. For the purpose of simplifying the drawing, only three objective lenses 6 are shown in FIG. 1, and the two objective lenses 6 located behind the three objective lenses are not shown in FIG. .

The sensitivity of the contact detection sensor 11 is detected by the detection circuit 12
It is represented by the output of A, and this output sensitivity is SV / μm (for example, 1 V / μm).

In the following description, the contact detection sensor 1
1 is a highly sensitive type (SV / μm = 1V / μm) as a representative example. However, regarding the contact detection sensor 11,
Since there is a low sensitivity type (SV / μm = 0.1V / μm), the characteristics of the bandpass filter (BPF) when the low sensitivity type contact detection sensor 11 is adopted will also be described later.

The moving speed of the stage 2 is changed according to the type of the objective lens 6 selected by the stage controller 14. That is, depending on the magnification of the objective lens 6,
The moving speed of the stage 2 is determined, and optimal focus control is executed for the selected objective lens 6. Here, the moving speed for each objective lens 6 is shown in Table 1 below.
It is set as shown in.

[0051]

[Table 1]

The stage moving speed in Table 1 is determined in proportion to the depth of focus of the objective lens.

The output of the detection circuit 12A corresponding to the sensitivity of the contact detection sensor 11 according to the stage moving speed becomes the output shown in Table 2 below according to the objective lens.

[0054]

[Table 2]

FIG. 4 shows a detection circuit 12 corresponding to the lapse of time from the start of the contact with the contact time being 0 and the sensitivity of the contact detection sensor 11 provided in each objective lens 6.
The relationship with the output (voltage) of A is shown. Here, when the threshold of the comparator 12B is r V (for example, 0.1 V), the time when the output of the detection circuit 12A for each objective lens reaches the threshold is shown in Table 3 below.

[0056]

[Table 3]

From the above, the type with high sensor sensitivity (SV /
In the detection system in which the contact detection sensor 11 (μm = 1V / μm) is adopted, the bandpass filter (BPF) is r
/ S ms to 20 r / S ms, for example, it is sufficient if it has a characteristic that allows passage of a changing detection signal in a time interval of 0.1 ms to 2 ms and suppresses signals corresponding to other noise. . That is, the bandpass filter (BPF) is S / 20r H
It suffices to allow the detection signal to pass in the frequency band of z to S / r Hz, for example, 500 Hz to 10 kHz, and reduce the other signals. Such a bandpass filter characteristic is as shown in FIG. This Figure 5
Bandpass filter (BPF) with characteristics shown in
Can be easily configured with a first-order low-pass filter and a first-order high-pass filter.

Low sensor sensitivity type (SV / μm = 0.
In the detection system in which the contact detection sensor 11 of 1 V / μm) is adopted, the bandpass filter (BPF) is r / S ms.
.About.20 r / S ms, for example, it is sufficient if it has a characteristic of permitting passage of a changing detection signal in a time interval of 1 ms to 20 ms and suppressing signals corresponding to other noises. That is, the bandpass filter (BPF) is S / 20r Hz ~
It suffices to allow passage of the detection signal in the frequency band of S / r Hz, for example, 50 Hz to 1 kHz, and reduce the other signals.

From the above, various types of sensor sensitivity (S
Considering that a contact sensor of V / μm = 0.1 to 1 V / μm) is used in the detection system, a bandpass filter (BP
F) has a characteristic that allows passage of a changing detection signal in a time interval of r / S ms to 20r / S ms, for example, 0.1 ms to 20 ms, and suppresses signals corresponding to other noises. That would be good. That is, bandpass filter (BPF)
Is S / 20r Hz to S / r Hz, for example, 50 Hz to 10 kHz
It suffices to allow the detection signal to pass in the z frequency band and reduce the other signals.

The filter circuit 12D shown in FIG. 2 may have a circuit configuration as shown in FIG. The filter circuit 12D includes five filters 12D1 to 12D5 corresponding to the five objective lenses 6 in order to detect a contact signal with higher accuracy and at higher speed.

These five filters 12D1 to 12D5
Have different filter characteristics, for example, different differential filter characteristics. This filter circuit 12
D includes a switch 12G that switches the switching contacts G1 to G5 corresponding to the selected objective lens 6 when the objective lens 6 is switched and one objective lens 6 is selected. Objective lens 6 and filter 12
D1 to 12D5 have the following correspondence.

5 × objective lens: 1st filter 12D1 10 × objective lens: 2nd filter 12D2 20 × objective lens: 3rd filter 12D3 50 × objective lens: 4th filter 12D4 100 × objective lens: 5th filter 12D5 where The characteristics of the first to fifth filters 12D1 to 12D5 will be described.

As described above, if the output of the detection circuit 12A corresponding to the sensitivity of the contact detection sensor 11 is SV / μm (for example, 1V / μm), the moving speed of the stage with respect to the objective lens 6 is as shown in Table 1. Is set to.

The output of the detection circuit 12A corresponding to the sensitivity of the contact detection sensor 11 has the relationship shown in Table 2 according to the objective lens. Further, the elapsed time from the start of contact of the sensor and the output (voltage) of the detection circuit 12A corresponding to the sensitivity of the contact detection sensor 11 provided in each objective lens 6 are as shown in FIG.
The relationship is as shown in. Furthermore, the time r / S ms (for example, 0.1 ms) at which the output of the detection circuit 12A with respect to the objective lens reaches the threshold value r V (for example, 0.1 V) has the relationship shown in Table 3.

Here, for simplification, the contact output signal shown in FIG. 4 (hereinafter, simply referred to as a linear signal) is replaced with a sine wave signal for consideration. FIG. 7 shows an output signal (straight line signal) of the detection circuit 12A corresponding to a 5 × objective lens and a threshold value r.
Time point at which V (eg 0.1V) is reached r / S ms (eg 0.1
It shows a sine wave signal that approximates the linear signal part up to ms). The amplitude of this sinusoidal signal is half the threshold r / so that the maximum slope matches the slope of the linear signal.
To 2 V (eg 0.05 V), its offset is r / 20
V, for example, 0.05V, and the reciprocal of the frequency becomes about three times (for example, frequency is 3.3kHz) for the linear signal to reach the threshold value rV (for example, 0.1V). There is.
In this replacement, the threshold value r V (for example, 0.1 V)
Although there will be a difference in the time to reach, this deviation will not be a problem as will be described later.

Similarly, when the output signals for the other objective lenses are replaced by sine waves, the frequencies of the sine wave signals replaced for the respective objective lenses have the relationship shown in Table 4 below.

[0067]

[Table 4]

Similarly, type SV / μm with low sensor sensitivity
If the same consideration is made for (for example, 0.1 V / μm), the frequency of the sine wave signal has the relationship shown in Table 5 below.

[0069]

[Table 5]

Based on the above consideration, each filter 12D1
.About.12D5 can be configured by a differentiator for detecting each sine wave signal at a higher speed and a second-order low-pass filter for further reducing noise. Specifically, as shown in FIG. 8, the first filter 12D1 corresponding to the 5 × objective lens 6 has a frequency S / 3r kHz (for example,
0.33 kHz to 3.3 kHz) with a gain × 2 differential characteristic and a second-order low-pass filter characteristic whose cutoff frequency is 10 times the sine wave frequency (for example, 3.3 kHz to 33 kHz). It is preferable. The second filter 12D2 corresponding to the 10 × objective lens 6 has a frequency S / 3 (2
r) A second-order low-pass filter with gain × 2 differential characteristics and a cutoff frequency of 10 times the sine wave frequency (for example, 1.65 kHz to 16.5 kHz) for a sine wave of kHz (for example, 0.16 kHz to 1.65 kHz). It is preferable that the characteristics are provided. The third filter 12D3 corresponding to the 20 × objective lens 6 has a frequency S / 3 (4r) kHz (for example, 0.0825).
(KHz to 0.825 kHz) with a gain × 2 differential characteristic and a second-order low-pass filter characteristic with a cutoff frequency 10 times the sine frequency (for example, 0.825 kHz to 8.25 kHz). It is preferable to have the following characteristics. Fourth filter 12D corresponding to the 50 × objective lens 6
4 is frequency S / 3 (10r) kHz (for example, 0.033 kHz to 0.33
The differential characteristic of gain × 2 and the cutoff frequency are 10 times the frequency of the sine wave (eg 0.33
It is preferable to have a characteristic having a second-order low-pass filter characteristic of (kHz to 3.3 kHz). Furthermore, a 100 × objective lens 6
The fifth filter 12D5 corresponding to is frequency S / 3 (20r) k
For a sine wave of Hz (for example, 0.0165 kHz to 0.165 kHz), a gain × 2 differential characteristic and a cutoff frequency of 10 times the frequency of the sine wave (for example, 0.165 kHz to 1.65 kHz) are 2
It is preferable to have a characteristic having the next low-pass filter characteristic.

FIG. 9 shows a sine wave signal indicated by a broken line obtained by replacing the linear signal of the sensor corresponding to the 5 × objective lens 6 and a signal waveform (the sine wave signal output after passing through the first filter 12D1). It is indicated by a solid line.). As shown in FIG. 9, the signal waveform that has passed through the first filter 12D1 has the same amplitude as the threshold value (for example, 0.1 V), does not include an offset, and has the same frequency as the original sine wave signal. Has become. Since the output signal waveform shown in FIG. 9 passes through the differentiator in the first filter, the direct current (DC) component is removed and its phase is π / 2.
The signal is advanced.

Here, the reason why the differential characteristic of each of the filters 12D1 to 12D5 is gain × 2 with respect to the frequency of the sine wave signal will be briefly described. The amplitude of the replacement sine wave signal is half the threshold value, so that the amplitude of the output signal output from the filter becomes equal to the threshold value. That is, in the filter
This is because the offset of half the threshold value is added to the replacement sine wave signal. Incidentally, if the gain is × 2 or more, the same effect can be obtained, but since noise of a frequency component corresponding to 0.5 to 100 times the frequency of the sine wave signal is also amplified in the same manner as the sine wave signal, It is desirable to set within approximately x10 times.

The reason why the cutoff frequency of the second-order low-pass filter for reducing noise is set to 10 times the frequency of the sine wave signal is that the frequency is close to the frequency of the sine wave signal (frequency range of 0.1 to 10 times). This is because the differential characteristic can be obtained completely in (), in other words, the characteristic of the second-order low-pass filter does not affect the sine wave signal. Further, regarding the time lag between the linear signal and the sine wave signal reaching the threshold value, the differentiator operates almost completely in the vicinity of the frequency of the sine wave signal (frequency range of 0.1 to 10 times). This is because the approximate deviation has no effect.

As described above, each of the filters 12D1-12
D5 differentiates each sine wave signal, so that it is possible to detect contact at high speed.
Moreover, since the noise of each sine wave signal can be reduced by the second-order low-pass filter of each filter,
The contact can be detected with higher accuracy.

In the microscope system according to the above-described embodiment, the contact detection sensor 11 has been described consistently. However, when the objective lens 6 touches the sample 4, a slight pressure due to the touch is detected. Different pressure sensors can also be used. Further, the example in which the contact detection sensor 11 is provided at the tip of the objective lens 6 has been described, but the contact detection sensor 11 (or the pressure sensor) may be provided on the stage 2. Contact detection sensor 1 on stage 2
1 (or pressure sensor), the frame body 40 is arranged on the stage 2 as shown in FIG. 10, and the ring-shaped contact detection sensor 11 (or pressure sensor) is provided inside the frame body 40. It is placed directly on top. A transparent support plate 41 is placed on the contact detection sensor 11 (or pressure sensor), and the support plate 4
The sample 4 is placed on the sample 1 and provided for observation by the objective lens 6. Then, in the transmissive light source system, the light beam is applied to the sample 4 through a light beam passage hole (not shown) provided in the stage 2 and the transparent support plate 41.

The support plate 41 may not be transparent but may have a through hole for the illumination light beam.

In the microscope system shown in FIG. 10, when the objective lens 6 of the microscope touches the sample 4, a slight pressure due to the touch is applied to the ring-shaped contact detection sensor 11 (or pressure sensor) via the support plate 41. Transmitted. Therefore, from the contact detection sensor 11 (or pressure sensor),
A detection signal associated with the contact is output. The processing of this output signal is the same as the description with reference to FIGS. 1 to 9, and therefore its description is omitted.

[0078]

As described above, according to the present invention, the contact between the object to be observed and the objective lens is detected with high accuracy, and it is possible to prevent the two from over-contacting and damaging one or both. It is possible to provide a microscope system having an over-contact prevention function that can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing a microscope system according to an embodiment of the present invention.

FIG. 2 is a block diagram schematically showing a contact determination unit according to one embodiment.

FIG. 3 is a graph showing gain characteristics of the filter circuit shown in FIG.

FIG. 4 is a graph showing a relationship between a lapse of time after the contact sensor starts contacting the sample and an output voltage of the detection circuit corresponding to the sensitivity of each contact sensor in the contact determination unit shown in FIG. .

5 is a graph for explaining bandpass characteristics of the filter circuit shown in FIG.

6 is a block diagram showing a filter circuit according to a modification of the contact determination unit shown in FIG.

7 shows an output signal of a detection circuit corresponding to a 5 × objective lens in the filter circuit shown in FIG. 6 and a sine wave signal approximated to a linear signal portion up to a time point r / S ms when a threshold value r V is reached. The waveform diagram shown.

8 is a graph showing the relationship between the gain and frequency of each filter in the filter circuit shown in FIG.

9 is a sine wave signal shown by a broken line obtained by replacing the linear signal of the sensor corresponding to the 5 × objective lens in the filter circuit shown in FIG. 6 and a signal obtained by passing the sine wave signal through the first filter. The figure which shows a waveform.

10 is a sectional view schematically showing a sensor mechanism according to a modified example of the microscope system shown in FIG.

[Explanation of symbols]

1 ... Microscope body 1A ... Base part 1B ... Body 1C: Objective arm 2 ... Stage 3 ... Stage motor 4 ... specimen 5 ... Electric revolver 6 ... Objective lens 7 ... AF unit 8 ... lens barrel 9 ... Eyepiece 10 ... Light source for transmission 11 ... Contact detection sensor 12 ... Contact determination unit 12A ... Detection circuit 12B ... Comparator 12C ... D / A converter 12D ... Filter circuit 12F ... A / D converter 12D1 to 12D5 ... Filter 12G ... switch 13 ... Objective lens switching mechanism controller 14 ... Stage control unit 15 ... CPU 16 ... User operation unit 40 ... Frame body 41 ... Support plate

Claims (11)

[Claims] 1. A microscope system in which an objective lens for observing an object to be observed is movable relative to a stage on which the object to be observed is mounted in the optical axis direction. A detection unit that detects a contact state with the objective lens and outputs a detection signal according to the contact state, and a DC that removes a DC component from the detection signal output from the detection unit to generate a contact determination signal. A component removing unit, a determining unit that determines, based on the contact determination signal, that the contact state between the observation object and the objective lens exceeds a predetermined value, and outputs an overcontact signal; And a control means for controlling relative movement of the stage and the objective lens in response to the microscope system. 2. A stage for placing an observation target object, a plurality of objective lenses for observing the observation target object, and one objective lens selected from the plurality of objective lenses to select this objective lens. Objective lens selecting means arranged on the optical axis of the microscope, moving means for relatively moving the selected objective lens with respect to the stage at a relative speed depending on the selected objective lens, and for each objective lens A detection element which is provided, detects a contact state between the observation object and the selected objective lens depending on the selection of the objective lens, and outputs a detection signal according to the contact state; Filter means for generating a contact determination signal from which a DC component is removed from the signal, and it is determined based on the contact determination signal that the contact state between the observation object and the objective lens exceeds a predetermined value. A microscope system comprising: a determination unit that sets a constant over-contact signal and outputs a control signal; and a control unit that controls the relative movement of the stage and the objective lens in response to the over-contact signal. 3. The microscope system according to claim 1, wherein the DC component removing means includes a high-pass filter that removes low frequency components. 4. The DC component removing means combines a differential gain characteristic, a proportional gain characteristic and an integral gain characteristic,
The microscope system according to claim 1, further comprising a bandpass filter that removes signals other than a predetermined frequency band. 5. The microscope system according to claim 1, wherein the contact determining means includes a contact determining signal from the DC component removing means and a comparator for comparing a preset threshold value. 6. The microscope system according to claim 1, wherein the detection unit includes a pressure sensor that detects a contact pressure corresponding to a contact state between the observation object and the objective lens. 7. The filter means comprises 50 Hz to 10 k
3. The microscope system according to claim 2, further comprising a bandpass filter that allows detection signals to pass in the frequency band of Hz and reduces signals other than that. 8. The bandpass filter is 500 Hz.
The microscope system according to claim 7, wherein a detection signal is allowed to pass in a frequency band of 10 kHz and signals other than that are reduced. 9. The bandpass filter is 50 Hz to
Allowing the detection signal to pass in the frequency band of 1 kHz,
The microscope system according to claim 7, wherein other signals are reduced. 10. If the detection means has a sensitivity of S (V / μm) and the predetermined value is r (V), the band pass filter has a frequency of S / 20r Hz to S / r Hz. The microscope system according to claim 2, wherein a detection signal in a band is allowed to pass and signals other than that are reduced. 11. The filter means includes a plurality of filters having filter characteristics corresponding to each of the objective lenses, and the detection means depends on the selected objective lens and corresponds to the objective lens. 3. The microscope system according to claim 2, further comprising switching means for selecting one filter and switching and supplying the detection signal to the selected filter.