JP2000227544A - Focusing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently detect focusing without troubling a user in focusing operation performed when plural objective lenses are switched by deciding the execution or the stop of the focusing operation for the objective lens based on the execution or the non-execution previously set every time the objective lens is switched. SOLUTION: Information whether or not focusing operation is executed to the respective objective lenses 4a to 4e is set in an objective lens setting device 34. Five objective lenses 4a to 4e are attached to five hole positions of an objective lens switching device 30, and whether or not the focusing operation is executed to the lenses 4a to 4e is set. A focusing switching decision device 33 decides the execution of the focusing operation or the stop of the focusing operation to the lenses 4a to 4e based on the information whether or not the focusing operation is executed to the respective lenses 4a to 4e previously set in the device 34 every time the lenses 4a to 4e are switched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focusing device for performing a focusing operation on a subject used in a magnifying optical system such as a microscope or an optical measuring device.

[0002]

2. Description of the Related Art As such a focusing apparatus, there is a technique of irradiating a measurement light onto an object surface through an objective lens and performing focusing on the object surface based on light reflected from the object surface. For example, it is known as JP-A-4-25711.

FIG. 7 is a block diagram showing an example of a focusing device.

A subject 2 is mounted on a stage 1. The stage 1 moves the distance between the objective lens 4 and the surface of the subject 2 in the optical axis direction (Z direction) by driving the driver 3.

The illumination optical system 5 causes illumination light emitted from an illumination light source 6 to enter an objective lens 4 via a lens 7 and a half mirror 8, and illuminates the subject 2 through the objective lens 4. .

The observation optical path system 9 is for observing an enlarged image of the subject 2 and is a dichroic mirror 10 that reflects only the wavelength component of the laser beam on the optical axis of the objective lens 4.
Through the lens 11, prism 12 and eyepiece 13
Is arranged.

On the other hand, a semiconductor laser 15 is provided in the focusing processing system 14, and a collimator lens 16 and a polarization beam splitter 17 are arranged on the optical axis of a laser beam emitted from the semiconductor laser 15. On the reflection optical path of the polarization beam splitter 17, a quarter-wave plate 18,
The dichroic mirror 10 is disposed, and the reflected light path of the dichroic mirror 10 coincides with the optical axis of the objective lens 4.

The subject 2 of the polarizing beam splitter 17
An imaging lens 19 and a beam splitter 20 are arranged on the transmitted light path of the reflected light from the light source. Of these, on the transmitted light path of the beam splitter 20, a distance L behind the focal point P of the imaging lens 19 is provided. A first stop 21 is provided, and a first light receiving element 22 is further provided. In addition, on the reflected light path of the beam splitter 20, a second stop 23 is disposed in front of the focal point Q of the imaging lens 19 by a distance L, and a second light receiving element 24 is disposed.

The first and second light receiving elements 22, 24
Are sent to the signal processing system 25.

The signal processing system 25 receives the electric signals A and B output from the first and second light receiving elements 22 and 24 and executes the calculation of (A−B) / (A + B). It has a function of outputting an error signal according to the displacement of the surface of the subject 2.

The operation of such a focusing device will be described.
A laser beam emitted from the semiconductor laser 15 (hereinafter, referred to as a laser beam)
The measurement light is shaped into parallel light by the collimator lens 16 and enters the polarization beam splitter 17.
The measurement light reflected by the polarization beam splitter 17 is
The light passes through the 波長 wavelength plate 18, is reflected by the dichroic mirror 10, and is focused on the surface of the subject 2 through the objective lens 14.

The reflected light reflected on the surface of the subject 2 is again reflected by the objective lens 4, the dichroic mirror 10,
The light enters the polarization beam splitter 17 via the 波長 wavelength plate 18.

FIG. 8 shows the polarization beam splitter 17.
From the laser beam incident on the 波長 wavelength plate 18
It indicates the direction of oscillation of the laser beam in relation to the reflected light incident on the polarizing beam splitter 17 from the wave plate 18,
2A shows the incident light side, and FIG. 2B shows the reflected light side. The X axis is the transmission direction component of the polarization beam splitter 17, and the Y axis is the reflection direction component of the polarization beam splitter 17. ing. As shown in the figure, the relationship between the incident light that enters the quarter-wave plate 18 from the polarization beam splitter 17 and the reflected light that enters the polarization beam splitter 17 from the quarter-wave plate 18 is represented by a quarter-wave plate 18. Is transmitted twice, so that the input linearly polarized light returns to the polarization beam splitter 17 as linearly polarized light having a vibration direction inclined by 90 degrees and is transmitted through the polarization beam splitter 17. It will be. After passing through the polarizing beam splitter 17, the reflected light passes through the imaging lens 19 and is split by the beam splitter 20 in two directions.

One of the reflected lights is transmitted to the imaging lens 19.
Is irradiated to the first light receiving element 22 through the first stop 21 disposed rearward by the distance L from the focal point P, and the other reflected light is forward by the distance L from the focal point Q of the imaging lens 19. The second light receiving element 2 through the second diaphragm 23
4 is irradiated.

The first and second light receiving elements 22, 24
Generates electric signals A and B corresponding to the amounts of light received from the surface of the subject 2 and receives the signals and sends them to the signal processing system 25.

The signal processing system 25 performs a predetermined operation on the electric signals A and B from the first and second light receiving elements 22 and 24, and outputs an error signal corresponding to the surface of the subject 2. I do. For example, if the electric signals A and B from the first and second light receiving elements 22 and 24 have characteristics as shown in FIG. 9, the signal processing system 25 detects the displacement of the surface of the subject 2. The calculation of (A−B) / (A + B) is performed as a signal to be detected,
An error signal that becomes 0 at the focal point F as shown in FIG. 10 is obtained.

The driver 3 receives the error signal from the signal processing system 25 and drives the stage 1 in the optical axis direction so that the surface of the subject 2 is located at a position where the error signal becomes zero. Then, the focusing operation is performed by relatively moving the distance between the objective lens 4 and the surface of the subject 2.

[0018]

As described above, the subject 2
Since the focusing operation is performed based on the amount of reflected light from the surface of the lens, when this focusing operation is applied to a microscope apparatus having a plurality of objective lenses, for example, when the objective lens 4 having an extremely large magnification is selected. In addition, since the amount of reflected light is small, the focusing operation can hardly be performed. In addition, since the focusing operation is performed on the position of the subject 2 where the measurement light is irradiated, for example, when the objective lens 4 having a large magnification is selected, the subject 2 or the film having the step is applied. In observing the subject 2 that is present, it may be preferable that the focusing operation is not performed.

As described above, there are a case where it is preferable to perform the focusing operation by the objective lens 4 and a case where it is preferable not to perform the focusing operation. Since the operation is not switched between the execution and the non-execution, the user must perform the switching between the execution and the non-execution of the focusing operation, and the operation is very troublesome.

It is therefore an object of the present invention to provide a focusing device capable of performing good focusing detection without bothering a user in a focusing operation performed when a plurality of objective lenses are switched.

[0021]

According to the present invention, the measuring light is condensed on the surface of the object through a desired one of a plurality of objective lenses, and is combined based on the reflected light from the surface of the object. In a focusing device that detects an error with respect to focus and moves the distance between the objective lens and the subject relatively in the optical axis direction according to the error, the focusing operation is performed for each of the plurality of objective lenses. Objective lens setting means for setting whether to perform or not to perform, and each time the objective lens is switched, execution of a focusing operation for the objective lens based on execution or non-execution of the focusing operation set for the objective lens setting means Or a focus switching determining means for determining whether to stop the focusing operation,
It is a focusing device provided with.

According to a second aspect of the present invention, in the focusing apparatus according to the first aspect, a focus correction storage means for storing a focus correction value between a plurality of objective lenses, and each time the objective lens is switched,
A focus correction unit that corrects the distance between the objective lens and the subject based on the focus correction value stored in the focus correction storage unit.

[0023]

(1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a configuration diagram of a microscope apparatus to which a focusing device is applied.

The objective lens switching unit 30 is an electric revolver that mounts a plurality of objective lenses, for example, five objective lenses 4a to 4e at five hole positions, and switches them electrically. The objective lens switching device 30 has a function of switching one of the objective lenses 4a,..., 4e designated by the objective lens switching indicator 31 as shown in FIG. 2 to the designated position.

The objective lens position type sensor 32 includes an objective lens 4a switched by an objective lens switch 30.
4e to determine the mounting position and output the determination signal. For example, the mounting position is constituted by three Hall elements, and the mounting position is determined by 3-bit data.

The focus changeover judging unit 33 determines whether each of the objective lenses 4a to 4e is set to carry out the focusing operation or not for each of the objective lenses 4a to 4e. Each time the lenses 4a to 4e are switched, a function is provided for determining whether to execute a focusing operation on the objective lenses 4a to 4e or to stop the focusing operation.

Further, the encoder 35 has a function of giving an instruction signal to the focus switching determination unit 33 during manual driving.

Next, the operation of the apparatus configured as described above will be described with reference to the flowchart of the objective lens switching operation shown in FIG.

First, in step # 1, information as to whether the focusing operation is performed or not performed for each of the objective lenses 4a to 4e is set in the objective lens setting unit 34. Here, five objective lenses 4a to 4e are attached to five hole positions of the objective lens switch 30, and the focusing operation is set for each of the objective lenses 4a to 4d. On the other hand, the non-execution of the focusing operation is set.

When the objective lens 4a is selected, a focusing operation on the objective lens 4a is performed in step # 2. That is, the measurement light emitted from the semiconductor laser 15 is shaped into parallel light by the collimating lens 16 and is incident on the polarization beam splitter 17, reflected by the polarization beam splitter 17, and reflected by the ４ wavelength plate 18.
The light is focused on the surface of the subject 2 through the dichroic mirror 10 and the objective lens 14.

The reflected light reflected on the surface of the subject 2 is again reflected by the objective lens 4, the dichroic mirror 10,
The light enters the polarization beam splitter 17 via the 波長 wavelength plate 18, passes through the polarization beam splitter 17, passes through the imaging lens 19, and is branched in two directions by the beam splitter 20.

One of the reflected lights is transmitted to the imaging lens 19.
Is irradiated to the first light receiving element 22 through the first stop 21 disposed rearward by the distance L from the focal point P, and the other reflected light is forward by the distance L from the focal point Q of the imaging lens 19. The second light receiving element 2 through the second diaphragm 23
4 is irradiated.

The signal processing system 25 applies (A−A) to each of the electric signals A and B from the first and second light receiving elements 22 and 24.
B) / (A + B) is calculated to obtain an error signal which becomes 0 at the focal point F as shown in FIG.

The driver 3 receives the error signal from the signal processing system 25 and drives the stage 1 in the optical axis direction so that the surface of the subject 2 is located at a position where the error signal becomes zero. Then, the focusing operation is performed by relatively moving the distance between the objective lens 4 and the surface of the subject 2.

The switching operation from the objective lens 4a to the objective lens 4b will be described.
Issues an instruction to switch to the objective lens 4b to the focus switching determination unit 33.

Since the focusing switch determination unit 33 sets the objective lens 4b to perform the focusing operation in the objective lens setting unit 34, the focusing operation performed by the objective lens 4a in step # 3. Abort the next step #
In step 4, the objective lens is switched from 4a to 4b by the operation of the objective lens switch 30.

At this time, the objective lens position type sensor 32
Determines the mounting position of the objective lens 4b switched by the objective lens switching device 30, and sends the determination signal to the focus switching determination device 33.

Upon receiving the discrimination signal from the objective lens position type sensor 32 and confirming the completion of the switching of the objective lens 4b, the focus switching determination unit 33 executes the focusing operation of the objective lens 4b in step # 5. Therefore, in the following step # 6, the focusing operation is performed again on the objective lens 4b. The focusing operation on the objective lens 4b is the same as the focusing operation on the objective lens 4a, and a description thereof will be omitted.
Therefore, after the switching from the objective lens 4a to the objective lens 4b, the focusing operation is still performed.

Next, the operation of switching from the objective lens 4a to the objective lens 4e will be described.
Issues an instruction to switch to the objective lens 4e to the focus switching determination unit 33.

In the focus switching determination unit 33, since the objective lens 4e is set in the objective lens setting unit 34 so that the focusing operation is not performed, the focusing performed by the objective lens 4a in step # 3. The operation is stopped, and in the next step # 4, the objective lens is switched from 4a to 4e by the operation of the objective lens switching unit 30.

At this time, the objective lens position type sensor 32
Determines the mounting position of the objective lens 4e switched by the objective lens switching device 30, and sends the determination signal to the focus switching determination device 33.

When the focusing switch judging unit 33 receives the discrimination signal from the objective lens position type sensor 32 and confirms the completion of the switching of the objective lens 4e, the focusing operation of the objective lens 4e is not performed in step # 5. Since it is determined that there is, the focusing operation for the objective lens 4e is not performed.

Therefore, after switching from the objective lens 4a to the objective lens 4e, the focusing operation is automatically disabled, and the stage 1 can be manually driven by the instruction signal from the encoder 35.

On the other hand, the switching operation from the objective lens 4e to the objective lens 4a will be described. Contrary to the above switching operation, the objective lens switching indicator 31 instructs the focus switching determiner 33 to switch to the objective lens 4a. Emits.

Since the focus switching determination unit 33 sets the objective lens 4a to execute the focusing operation in the objective lens setting unit 34, the focusing operation performed by the objective lens 4e in step # 3. Abort the next step #
In step 4, the objective lens is switched from 4e to 4a by the operation of the objective lens switching unit 30.

At this time, the objective lens position type sensor 32
Determines the mounting position of the objective lens 4a switched by the objective lens switching device 30 and sends the determination signal to the focus switching determination device 33.

Upon receiving the discrimination signal from the objective lens position type sensor 32 and confirming the completion of the switching of the objective lens 4a, the focus switching determination unit 33 executes the focusing operation of the objective lens 4a in step # 5. Therefore, the focusing operation on the objective lens 4a is performed again. The focusing operation for the objective lens 4a is as follows.
This is the same as above, and the description is omitted here. Therefore, after switching from the objective lens 4e to 4a, the focusing operation is automatically performed.

As described above, in the first embodiment, each time the plurality of objective lenses 4a to 4e are switched, these objective lenses 4a to 4e are switched based on the execution or non-execution of the focusing operation set in the objective lens setting unit 34. Since the execution of the focusing operation on the lenses 4a to 4e or the stop of the focusing operation is determined, for example, when the objective lens 4 having an extremely large magnification is selected, the amount of reflected light becomes small, so that the focusing operation can hardly be performed. When the objective lens 4 having a large magnification is selected, or when the subject 2 having a step or the subject 2 on which a film is formed is observed, it is preferable that the focusing operation is not performed. In some cases, it is preferable that the focusing operation is performed by the objective lens 4 and that the focusing operation is not performed. Must be carried out instead, automatically can better focus detection that operation in not very cumbersome, it is its good observation.

(2) Next, a second embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 4 is a configuration diagram of a microscope apparatus to which a focusing device is applied.

The parallax correction table 36 stores in advance parallax correction values between the objective lenses 4a to 4e.

The focus switching judging unit 37 determines whether each objective lens 4a to 4e is set to carry out a focusing operation or not for each objective lens 4a to 4e in advance. Each time the lenses 4a to 4e are switched, the objective lenses 4a to 4e have a function of determining whether to perform a focusing operation or stop the focusing operation, and each objective lens 4a stored in the focusing correction table 36 in advance.
It has a function of performing a parfocal correction operation based on the parfocal correction values between 4e and 4e.

The parfocal correction operation will be described. The objective lens is originally manufactured such that the distance from the mounting surface of the microscope to the focal position is a predetermined length as shown in FIG. Objective lenses such as objective lenses 4a, 4
There is a slight shift (parity shift) due to b. When switching from the objective lens 4a having the parfocal shift to the objective lens 4b, even if the objective lens 4a before the switch is in focus, the focus is shifted by the parfocal shift in the objective lens 4b after the switch.
It is necessary to adjust the distance between the objective lens 4b and the subject 2 by the amount of the parallax shift. This adjustment is a parallax correction operation. Therefore, the parallax correction value is stored in the parallax correction table 36 in advance.

Next, the operation of the apparatus constructed as described above will be described with reference to the flowchart of the objective lens switching operation shown in FIG. The description of the same operation as in the first embodiment will be omitted.

The operation of switching from the objective lens 4a to the objective lens 4b will be described. The objective lens switching indicator 31 issues an instruction to switch to the objective lens 4b to the focus switching determiner 33, and this focus switch determiner Since the objective lens setting unit 34 sets the objective lens 4b to perform the focusing operation in the objective lens setting unit 33, the focusing operation performed by the objective lens 4a is stopped in step # 3, and the next step # 4 Then, the objective lens is switched from 4a to 4b by the operation of the objective lens switching device 30.

At this time, the objective lens position type sensor 32
Determines the mounting position of the objective lens 4b switched by the objective lens switching device 30, and sends the determination signal to the focus switching determination device 33. Then, the focus switching determination unit 33 receives the determination signal from the objective lens position type sensor 32 and confirms the completion of the switching of the objective lens 4b.

Next, in step # 7, the focus switching determination unit 37 performs a focus correction operation based on a focus correction value between the objective lenses 4a and 4b stored in the focus correction table 36 in advance. A command is issued to the driver 3. As a result, the distance between the objective lens 4b and the subject 2 is adjusted by an amount corresponding to the defocus of the table 1 with respect to the objective lens 4b after switching the optical axis.

Next, the focus switching determination unit 37 determines in step # 5 that the objective lens 4b is to perform a focusing operation. Therefore, in step # 6, the focus switching determination unit 37 focuses on the objective lens 4b. Re-execute the operation. Thus, after the switching from the objective lens 4a to the objective lens 4b, the focusing operation is still performed.

Next, the operation of switching from the objective lens 4a to the objective lens 4e will be described. The focus switching determination unit 33 sets the objective lens setting unit 34 so that the objective lens 4e does not perform the focusing operation. Therefore, the focusing operation performed by the objective lens 4a is stopped in step # 3, and the objective lens is switched from 4a to 4e by the operation of the objective lens switch 30 in the next step # 4. Then, the focus switching determination unit 33 receives the determination signal from the objective lens position type sensor 32 and confirms the completion of the switching of the objective lens 4e.

Next, in step # 7, the focus switching determination unit 37 performs a focus correction operation based on a focus correction value between the objective lenses 4a and 4e stored in the focus correction table 36 in advance. A command is issued to the driver 3. As a result, the distance between the objective lens 4e and the subject 2 is adjusted by the same defocus as to the objective lens 4e after the table 1 has switched the optical axis.

Next, the focus switching judging unit 37 judges that the focusing operation of the objective lens 4e is not performed in step # 5, so that the focusing operation for the objective lens 4e is not performed.

Therefore, after switching from the objective lens 4a to the objective lens 4e, the focusing operation is automatically disabled, and the stage 1 can be manually driven by the instruction signal from the encoder 35.

On the other hand, the operation of switching from the objective lens 4e to the objective lens 4a will be described. The focus switching determination unit 33 is set in the objective lens setting unit 34 so that the objective lens 4a performs the focusing operation. In step # 3, the focusing operation performed by the objective lens 4e is stopped, and in the next step # 4, the objective lens is switched from 4e to 4a by the operation of the objective lens switching unit 30, and discrimination from the objective lens position type sensor 32 is performed. Receiving the signal and the objective lens 4a
Check that the switching is completed.

Next, in step # 7, the focus switching determination unit 37 performs a focus correction operation based on the focus correction value between the objective lenses 4e and 4a stored in the focus correction table 36 in advance. A command is issued to the driver 3. As a result, the distance between the objective lens 4a and the subject 2 is adjusted by an amount corresponding to the defocus of the table 1 with respect to the objective lens 4a after the switching of the optical axis.

Next, the focus switching determination unit 37 determines in step # 5 that the objective lens 4a is to perform a focusing operation, so that the focusing operation for the objective lens 4a is performed again. Thereby, after switching from the objective lens 4e to 4a, the focusing operation is automatically performed.

As described above, according to the second embodiment, the same effects as those of the first embodiment can be obtained, and the objective lenses 4a to 4e for which the focusing operation is performed and which are not performed are provided. When switched, the parfocal correction is performed, and the parallax shift of the individual objective lenses 4a to 4e can be automatically adjusted.

The present invention is not limited to the first and second embodiments, but may be modified as follows.

For example, in the first and second embodiments, a case has been described in which one type of focusing operation is performed or not performed for one objective lens. A set value may be provided for each method.

In the first and second embodiments,
Although the focus determination is performed using the two light receiving elements 22 and 24, the number is not limited to the number. Also, a well-known method such as a pupil division method may be applied to the focus detection method.

The driver 3 does not drive the stage 1 in the optical axis direction, but may move the objective lens in the optical axis direction.

[0072]

As described above in detail, according to the first aspect of the present invention, good focus detection can be performed without bothering the user in the focus operation performed when a plurality of objective lenses are switched. A focusing device can be provided.

Further, according to the second aspect of the present invention, it is possible to provide a focusing device capable of automatically performing the in-focus correction when switching to each objective lens.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing an objective lens switching indicator.

FIG. 3 is a flowchart of an objective lens switching operation.

FIG. 4 is a configuration diagram showing a second embodiment of a microscope device to which a focusing device according to the present invention is applied.

FIG. 5 is a diagram for explaining a parfocal correction operation.

FIG. 6 is a flowchart of an objective lens switching operation.

FIG. 7 is a configuration diagram of a conventional focusing device.

FIG. 8 is a diagram showing a relationship between a laser beam that enters a quarter-wave plate from a polarizing beam splitter and reflected light that enters a polarizing beam splitter from a quarter-wave plate.

FIG. 9 is a view showing characteristics of respective electric signals of the first and second light receiving elements.

FIG. 10 is a diagram showing an error signal obtained by calculation of a signal processing system.

[Explanation of symbols]

 1: stage, 2: subject, 3: driver, 4, 4a-4e: objective lens, 5: illumination optical system, 9: observation optical path system, 10: dichroic mirror, 14: focusing processing system, 15: Semiconductor laser, 16: collimator lens, 17: polarization beam splitter, 18: 1/4 wavelength plate, 19: imaging lens, 20: beam splitter, 21: first stop, 22: first light receiving element, 23: Second diaphragm, 24: second light receiving element, 25: signal processing system, 30: objective lens switching device, 31: objective lens switching indicator, 32: objective lens position type sensor, 33, 37: focus switching determination , 34: Objective lens setting unit, 35: Encoder, 36: Parfocal correction table.

Claims (2)

[Claims] 1. A measuring light is condensed on a surface of a subject through a desired one of a plurality of objective lenses, and an error with respect to focusing is detected based on light reflected from the surface of the subject.
In a focusing device that performs a focusing operation of relatively moving the distance between the objective lens and the subject in the optical axis direction according to the error, the focusing operation may be performed for each of the plurality of objective lenses or may not be performed. An objective lens setting unit that sets whether to perform the operation, and each time the objective lens is switched, the focusing operation for the objective lens is performed based on the execution or non-execution of the focusing operation set in the objective lens setting unit. A focusing switch determining unit for determining whether to perform or stop the focusing operation. 2. A focus correction storage means for storing a focus correction value between a plurality of the objective lenses, and a focus correction value stored in the focus correction storage means each time the objective lens is switched. Parfocal correction means for correcting the distance between the objective lens and the subject based on the
The focusing device according to claim 1, further comprising: