JPH11249027A - Automatic focusing microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and surely set the offset adjustment of a focusing position to all the samples which can be automatically focused by adjusting the focal distance of a correction lens group and electrically driving a focal distance adjusting mechanism in accordance with the magnification of each objective lens. SOLUTION: A control part 25 gives a driving instruction to a correction lens driving part 20 to drive a color correction lens motor 17, to adjust the moving amount of a color correction lens group 9 in the optical direction and to correct the image forming position of a P.D.14. Since the corrected moving amount is different between the objective lenses 3a and 3b, respectively, it is stored in the every lenses to be used 3a and 3b. In such a way, since the optimum adjustment is performed for every magnification of the lenses 3a and 3b, the offset operation is always performed by the fixed moving amount of the lens regardless of the kinds of the lenses 3a and 3b. Therefore, the offset adjustment is always easily and surely set to all the samples in surplus adjusting width.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing microscope capable of automatically adjusting a focus position of an observation sample.

[0002]

2. Description of the Related Art At present, microscopes capable of observing minute materials or recording observation images as video images are widely used in research fields in the biological field and in inspection processes in the industrial field. When using such a microscope,
Usually, the focusing operation is performed by adjusting the focus of the observation sample by operating the focusing handle. However, since this operation is a manual operation, a considerable amount of skill is required to quickly perform the focusing operation, particularly when the depth of focus is small and the focusing range is narrow as in a high-magnification objective lens.

[0005] If the operability of the focusing operation is poor, it has an adverse effect of fatigue of the operator and a decrease in production efficiency. In particular, in a routine operation such as an inspection process, it is very important to perform this operation quickly to shorten the inspection time.

Therefore, various microscopes having an automatic focusing function capable of automatically performing such a focusing operation have been proposed, and many proposals have been made to improve them.

In Japanese Patent No. 2614843, a wavelength difference between infrared light for focus detection and visible light to be actually observed is corrected, and the chromatic aberration of each objective lens when a plurality of objective lenses are used is used. Means for compensating for variations in focus detection positions are described, and improvements in operability and reduction in manufacturing cost have been proposed.

Japanese Patent Application Laid-Open No. HEI 6-281409 discloses a method for detecting a defect in each layer of a sample having a step, such as a semiconductor wafer having a plurality of layers, without omission.

In Japanese Patent Application Laid-Open No. 8-43717, the focus position is determined by dividing the optical path on the detection side into two and obtaining detection signals from different light receiving elements using two types of imaging lenses having different magnifications. This is done over a wider area to improve sample compatibility.

[0008]

In the system proposed in the above-mentioned Patent No. 2614843, an adjusting unit is provided for each objective lens, and an offset value from a focus position is set for each objective lens. Since it can be reproduced, it is sufficiently effective for correcting the chromatic aberration of the objective lens.

However, no consideration is given to the displacement of the focal point due to the variation of the sample itself. This is effective, for example, for observing the top and bottom of a step of a sample having a step on the surface such as a semiconductor wafer. Is disadvantageous in that it is out of focus. In this case, in order to observe the other in-focus position, it is necessary to operate the adjustment unit provided for each objective lens to shift the optimal in-focus position for observation, or to temporarily stop the automatic focus detection operation and manually As a result, the user is forced to focus on the camera.

The above-mentioned Japanese Patent Application Laid-Open No. 6-281409 describes an inspection apparatus for observing a plurality of focal positions, which is effective for a complete routine inspection of a specific sample. In other words, this is an effective means for inspection of a single specimen in which the steps of the multilayer surface are known in advance. However, there is a disadvantage that when the shape of the sample changes, such as when observing another sample having a different level difference or when the thickness of the sample is unknown, it is not possible to take a quick response. In other words, in order to enable observation, it is necessary to change the focus offset value or re-register the focus offset value.However, no consideration has been given to the setting method, etc., and in the worst case, the setting operation must be performed with the observer. In some cases, another technician who is familiar with the device must perform the operation.
Therefore, when a plurality of specimens must be observed, it cannot be adapted.

By the way, in this type of focus detection device, due to its optical characteristics, the range in which the in-focus position can be determined becomes narrower as the objective lens has a higher magnification. This is because the imaging lens on the detection side has a fixed magnification, so that the above-mentioned Patent No. 2614843 and JP-A-6-28140 are disclosed.
In the two inventions of No. 9, even if the offset and the focal position of each objective lens can be corrected, the range and speed of the focus determination according to the magnification of the optical system such as the objective lens,
Performance, such as accuracy, will fluctuate.

In JP-A-8-43717, in order to avoid the above-mentioned problem, the optical path on the detection side is divided into two, and the photoelectric conversion is performed using two types of imaging lenses having different magnifications. Focus determination is performed based on two types of detection signals from the elements. However, with such a configuration, it is inevitable that at the same time, the size of the entire apparatus is increased and the price is increased due to an increase in the number of optical systems and light receiving elements. In addition, since each imaging lens is also a fixed magnification, it is not enough to secure an optimum focusing operation according to various magnifications.

Further, when the focus of the imaging lens is shifted by moving the position of the imaging lens on the detection side, the movement width differs between the case where the imaging lens has a low magnification and the case where the imaging lens has a high magnification. Therefore, there is a possibility that the focus offset value cannot be set satisfactorily in the configuration disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-281409.

The present invention has been made in view of the above-described circumstances, and has as its object to always focus on a wide range regardless of the magnification of an objective lens and the thickness of a sample when performing automatic focus detection. While ensuring the judgment range, it is possible to perform the focusing operation to the arbitrary position in the optical axis direction that the user wants to observe reliably and at high speed, while always having a margin regardless of the magnification of the objective lens, etc. An object of the present invention is to provide an autofocus microscope excellent in operability, in which offset adjustment of a focus position can be easily and reliably set for any sample that can be autofocused by a width.

[0015]

According to the first aspect of the present invention,
An observation optical system for observing light from the sample by irradiating the sample with visible light through one of a plurality of interchangeable objective lenses, and projecting non-visible light onto the sample through the objective lens in the observation optical system. A light source that emits light, a photoelectric converter that is arranged on an image plane of a light image of the non-visible light reflected by the sample, and outputs a signal corresponding to a position in the image plane of the non-visible light, and the photoelectric converter A microscope comprising: a focus position adjusting means for adjusting a focus position of a sample based on an output signal from the camera; and a correcting means for correcting a shift of non-visible light with respect to visible light of each objective lens by a correction lens group. In the focus detection device used in the above, the correction means includes a focal length adjustment mechanism for adjusting a focal length of the correction lens group, and a drive for electrically driving the focal length adjustment mechanism according to a magnification of each of the objective lenses. With means Characterized in that was.

As a result of this configuration, when performing automatic focus detection, the user can observe a wide focus determination range while securing a wide focus determination range regardless of the depth of focus or the thickness of the sample depending on the magnification of each objective lens. Focusing operation to the desired optical axis position can be performed reliably and at high speed, and even when adjusting the offset of the focus position, regardless of the objective lens magnification etc., it can be applied to any sample that can be automatically focused. On the other hand, it is possible to set easily and reliably with an adjustable width that always has a margin.

According to a second aspect of the present invention, in the first aspect of the present invention, the correction means moves the correction lens group to an arbitrary position within a predetermined range in the optical axis direction. And a driving means for electrically driving the correction lens group moving mechanism by a signal from an input unit operated by an observer.

As a result of such a configuration, the above-mentioned claim 1 is obtained.
In addition to the operation of the invention described above, it is possible to perform the offset adjustment of the focus position, which is more excellent in operability. According to a third aspect of the present invention, in the first or second aspect of the present invention, the correction means is provided when the position of the correction lens group reaches one of both ends of a driving range of the focal length adjusting mechanism. Is further provided.

As a result of such a configuration, the above-mentioned claim 1 is obtained.
In addition to the effect of the invention described in the item 2, when the position of the correction lens group reaches one of both ends of the driving range, this can be immediately recognized, so that the operability is further improved and the efficiency is further improved. Observation and the like can be carried out.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG.
Shows the entire configuration thereof, and a plurality of objective lenses 3a,
3b, a revolver main body 2 to which the plurality of objective lenses 3a and 3b can be attached, a revolver motor 15 for rotating the revolver main body 2 and electrically driving to insert an arbitrary objective lens 3 into an optical path; And revolver body 2
An electric revolver is constituted by a revolving hole position detector 21 for detecting which of the objective lens mounting positions is currently inserted in the optical path.

However, in this electric revolver, the revolver motor 15 is driven to rotate by the drive control of the revolver motor drive unit 18 which receives a signal from the control unit 25, and the objective lens 3 is located at any hole position of the revolver main body 2. The content detected by the revolving-hole-position detecting unit 21 for setting whether or not it is mounted is sent to the control unit 25 as it is.

The control section 25 is a well-known CPU circuit, as shown in FIG. 2, a CPU main body 28, a ROM 29 storing a program for controlling the system, and a volatile memory for storing data necessary for control as needed. RAM
30, an I / O port 31 for inputting / outputting a control signal, a data bus 32 for connecting them, and well-known peripheral circuits such as an oscillator and an address decoder (not shown). And the peripheral devices are controlled from the data bus 32.

An observation sample S to be observed is placed on the sample moving stage 1 and can be observed by the objective lens 3. The sample moving stage 1 is connected to a focusing motor 16 so that the sample moving stage 1 can be electrically moved up and down in a direction perpendicular to the optical axis. The focusing motor 16 includes a focusing motor driving unit 19.
The focusing motor drive unit 19 is controlled by the control unit 25 via the I / O port 31.

Reference light source 4 used for autofocus
As a light source, a light source in a wavelength region of non-visible light such as infrared light is used. The reference light source 4 performs pulse lighting of the light source and is controlled by a light source driving unit 22 that controls the intensity of the light source. The laser light emitted from the reference light source 4 is a collimating lens 5 for keeping parallel light. Through the light emitting side stopper 6 that cuts half of the light flux
, Only the P-polarized component is reflected and guided to the sample side. That is, the light beam once collected by the condenser lens group 8 passes through the color correction lens group 9 and passes through the λ / 4 plate
Is polarized and reflected by the dichroic mirror 11.

The color correction lens group 9 has both a zoom mechanism for changing the focal length by the color correction lens motor 17 and a mechanism for moving in the direction perpendicular to the optical axis. , And is driven by the color correction lens motor drive unit 20. The limit detection units 3 are provided at both ends of a predetermined range of the color correction lens group 9 in the optical axis direction.
3 is provided to limit the moving range of the color correction lens group 9 in the optical axis direction.

The dichroic mirror 11 has such a property that only the infrared region is reflected and the visible region passes. Thereby, the infrared light for autofocus is reflected by the dichroic mirror 11, and visible light for observing the sample, that is, observation light and illumination light, is not shown here via the objective lens 3 inserted in the optical path. It becomes possible to observe the eyepiece. The light beam reflected by the dichroic mirror 11 forms a spot-like image on the observation sample S by the objective lens 3. Then, the light beam reflected by the observation sample S is again polarized by 45 ° when it passes through the λ / 4 plate 10 again via the objective lens 3 and the dichroic mirror 11, and switches to the S-polarized component. After that, returning to the color correction lens group 9 and the condenser lens group 8, the PBS
7 is incident. Here, since the light beam is an S-polarized component as described above, the light beam passes through the PBS 7 as it is, passes through the light-receiving-side stopper 12, and the condenser lens group 13, and then becomes a photodiode (hereinafter abbreviated as "PD"). 14 is formed. P. D. Reference numeral 14 denotes a photodetector in which two photodiodes (sensors A and B) are arranged around the optical axis. P.
D. The current signal corresponding to the light intensity of the spot formed at 14 is subjected to current / voltage conversion by the amplifier 23, then amplified with a predetermined amplification factor, and then converted by the A / D converter 24 to a digital value. The arithmetic processing is performed by the control unit 25.

The operation unit directly operated by the observer includes an objective lens conversion switch (not shown) for rotating the revolver main body 2 to change the objective lens 3 inserted in the optical path to an arbitrary magnification. , An auto focus switch to set / cancel the auto focus operation,
And a JOG encoder (E) 27 for instructing the vertical movement of the focusing unit and the movement of the color correction lens group 9 are provided.
Among them, the encoder signal of the JOG encoder 27 is converted into the number of pulses by the pulse counter 26 and sent to the control unit 25. The control unit 25 reads the number of pulses from the pulse counter 26 to determine in which direction and how much the JOG encoder 27 has been rotated, and moves each drive unit according to the amount of rotation of the JOG encoder 27. It has become.

Next, a description will be given of a case where an autofocus operation is performed, particularly in the first embodiment. When an auto focus switch (not shown in FIG. 1) is pressed, the control unit 25 sends a signal to the light source driving unit 22 to irradiate the observation sample S with an infrared light spot for auto focus, and Start oscillation.

The spot is illuminated on the observation sample S with the light beam from the reference light source 4 and its reflection is D. The actual autofocus control is performed based on the position of the projected spot.

Here, the principle of the autofocus operation described in the present embodiment will be briefly described. Now, if the position of the sample moving stage 1 is above the in-focus position,
That is, assuming a case close to the objective lens 3, the spot from the reference light source 4 is quickly reflected from the observation sample S,
P. D. The spot image formed on the image 14 is formed as shown in FIG. 3A from the center position toward the sensor B and with reduced intensity.

On the other hand, when the sample moving stage 1 is located below the in-focus position, that is, when the sample moving stage 1 is far from the objective lens 3, the spot is imaged near the sensor A as shown in FIG.

When the sample moving stage 1 is at the correct focus position, the shape of the spot is approximately at the center of the optical axis within a uniform range for both the sensors A and B as shown in FIG. I do. Moreover, in this case, the light intensity at the center is the highest because it is at the focal position.

While judging the movement and strength of such spots, the control unit 25 moves the sample moving stage 1 to a point where the following equation {(AB) / (A + B)} = 0, thereby automatically controlling the position. Perform focus operation. When the output of the sensor A is large, the sample moving stage 1 is driven upward, and when the output of the sensor B is large, it moves downward. Thus, observation sample 1
The surface can be accurately focused.

However, one major problem occurs here. That is, since the reference light source 4 for performing the autofocus operation is infrared light and has a different wavelength from the actual visible light, it is out of focus in the visible light region even if the autofocus device determines that the subject is in focus due to chromatic aberration. Things happen. The color correction lens group 9 is installed there.
The control unit 25 gives a drive instruction to the correction lens driving unit 20 and drives the color correction lens motor 17 to adjust the amount of movement of the color correction lens group 9 in the optical axis direction.
D. The correction of the imaging position of No. 14 is performed. Since this correction movement amount can be limited to some extent by the characteristics of the objective lens 3 and the wavelength used by the reference light source 4, the correction movement value for each objective lens is previously stored in the ROM 29 or another storage medium, for example, a non-volatile memory when the apparatus is assembled and adjusted. By storing the data in an EEPROM or the like, a correction operation can be performed based on the data. Further, since the amount of correction movement differs for each objective lens 3, it is stored for each objective lens 3 used.

The color correction lens group 9 has another important role. Hereinafter, this role will be described. Sensor A from the photodetector input to the control unit 25,
Both output signals of B have characteristics as shown in FIG.
The signal processed by the control unit 25 has characteristics as shown in FIG. That is, the shape of the signal when the high-magnification objective lens is mounted is greatly different from the shape of the signal when the low-magnification objective lens is mounted.
That is, the range in which the signal appears in the vertical direction of the stage is reduced. This is due to the difference in NA between the objective lenses. The signal detected using the high-magnification objective lens having a large NA has a narrower distance between peaks in each signal, and further increases and decreases steeply. Will be presented.

Generally, in the in-focus position detecting device, FIG.
Alternatively, since the in-focus position is determined using one or both of the signals as shown in FIG. 4 (b), if the detectable range of these signals is narrow, it takes time to search the range. Spend, and as a result, it takes time to determine the focus.

This problem can be avoided by providing the color correction lens group 9 with a zoom function as focal length adjusting means. That is, the low-magnification objective lens has a color correction lens group 9.
By reducing the focal length of the objective lens and increasing the focal length when a high-magnification objective lens is attached, the variation in the shape of the detection signal due to the difference in NA between the objective lenses is eliminated, and a sufficient focus determination range is always secured It is possible to do. The focal length correction value of the color correction lens group 9 can be specified by the type of the objective lens, as in the case of the correction movement amount described above.
If the storage is set for each objective lens 3 used in the OM 29 or other storage medium, for example, an EEPROM or the like which is a nonvolatile memory, a correction operation based on the stored data can be performed. Thereby, focusing on the observation image is completed.

Therefore, before the autofocus operation is started in the present embodiment, the color correction lens group 9 is based on the correction movement value and the focal length correction value corresponding to each of the mounted objective lenses 3. And an optimal autofocus operation environment corresponding to each objective lens 3 is set.

With the above-described automatic adjustment of the color correction lens being performed, focusing on the observation image is finally completed. Finally, the operation at the time of objective lens conversion during the autofocus operation will be described.

If the changeover switch of the objective lens 3 (not shown) is pressed during the autofocus operation, the control unit 25 first stops the oscillation of the light source drive unit 22 and performs the A / D converter 24 when performing the objective conversion operation. And the arithmetic processing are stopped, and the ongoing autofocus operation is temporarily stopped. Then, the revolver motor driving unit 18 is driven, and the revolver motor 15 is driven.
Gives a rotation instruction to the revolver main body 2. When the rotation of the revolver main body 2 is completed and a new objective lens 3 is inserted into the optical path, the control unit 25 sets the revolving hole position detecting unit 2
1 is read, the magnification of the objective lens 3 currently inserted in the optical path is confirmed, and each correction value of the chromatic aberration correction lens group 9 corresponding thereto is read from the ROM 29 or a non-volatile memory (not shown). After driving the correction lens drive unit 20 to rotate the color correction lens motor 17 to adjust the focal length and position of the color correction lens group 9, the autofocus operation is restarted.

Thus, according to the present embodiment, when performing automatic focus detection, irrespective of the magnification of the objective lens and the thickness of the sample, the user can observe any desired focus determination range while securing a wide focus determination range. This makes it possible to perform the focusing operation to the position (Z direction) reliably and at high speed.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In the second embodiment, an offset mechanism during an autofocus operation will be described. Note that the autofocus operation itself is the same as that of the first embodiment, and the entire configuration is the same as that of FIGS. 1 and 2, and the same parts are denoted by the same reference numerals. Illustration and explanation are omitted.

However, there is a concern about whether or not the operator actually focuses on the part to be observed, which is generated when the autofocus operation is performed in the same manner as in the first embodiment and the focusing is completed. That is, the spot diameter applied to the observation sample S is very small, and the spot does not always hit the site observed by the actual worker. When there are many steps in the spot, etc. D. In some cases, an accurate output cannot be obtained from. In order to solve this, in the present embodiment, the following operation is performed during the autofocus operation.

During the auto focus operation, the control unit 25 sets the P.O. D. At the same time as the focus detection operation is performed based on the input from, the data of the pulse counter 26 is read and the JOG encoder 27 is monitored. When a signal according to the rotation instruction is generated by the JOG encoder 27, the control unit 25 receiving the signal gives a driving instruction to the correction lens driving unit 20, and only the position of the color correction lens group 9 is fixed while the focal length of the color correction lens group 9 is fixed. Move. Thus, when the color correction lens group 9 moves during the autofocus operation,
Naturally P. D. The spot shape to 14 changes.
In response to this, the control unit 25 gives a drive signal to the focusing motor drive unit 19 to move the sample moving stage 1. By repeatedly performing such an operation, an offset value is additionally set from the in-focus position detected by the apparatus, so that the operator can focus on a part to be observed. In addition, when the position of the color correction lens group 9 in the optical axis direction reaches one of both ends of the previously limited range due to the offset operation by the operator,
A signal is sent to the control unit 25 by the limit detection unit 33, and the control unit 25 receives the signal and notifies the worker to that effect using means such as a warning lamp or a buzzer of an operation unit (not shown).

The offset value determined by the operation, that is, the moving amount of the color correction lens group 9 in the optical axis direction is stored in the RAM 30 for each objective lens even after the objective lens is changed.
In the case of returning to the same objective lens, for example, after changing the objective lens to a desired magnification, the color correction lens group 9 is moved to the position of the corresponding offset value, and the autofocus operation is restarted. Therefore, even when the objective lens is changed, it is possible to always perform the observation that is accurately focused on the position to be observed.

What should be considered here is the offset adjustment width and resolution for each objective lens. That is, in the conventional color correction lens with a fixed magnification, since the shape of the detection signal differs depending on the magnification of the objective lens, particularly, NA, as described above, the moving amount of the color correction lens in offset adjustment for each objective lens is very different. . For example, if it is desired to perform autofocus on a sample at a position shifted by 1 μm from the current focus position, the color correction lens may be moved on the order of μm with a low-magnification objective lens.
A high-magnification objective requires a moving distance on the order of mm.
Such things can happen. As a result, with a high-magnification objective lens, it is conceivable that an increase in time spent for offset adjustment and a range in which offset can be performed are limited, and a satisfactory function cannot be performed.

However, in the apparatus of the present embodiment, the color correction lens group 9 is provided with a focal length adjusting mechanism, and the optimal adjustment is made for each magnification of the objective lens. The offset operation can be performed with the amount of lens movement. Therefore, if the range in which the color correction lens group 9 can be moved is widened without depending on the magnification of the objective lens, the range in which the offset can be performed is as follows.
As a result, a marginal offset operation is possible for any objective lens of any magnification.

However, since the movement amount here is an offset value depending on the sample and the observation place, it is inherent in the apparatus itself due to chromatic aberration described in the first embodiment. It should be added that the offset value is basically different from the offset value. Therefore, when data is stored in the RAM 30, it is desirable to store and save the data as separate data.

Thus, according to the present embodiment, even when adjusting the focus position offset during the operation of the auto farcus, any sample that can be automatically focused with a sufficient adjustment width regardless of the magnification of the objective lens and the like is always provided. By providing means that can be set easily and reliably for and by adding a limit warning function in offset operation,
A microscope which is easy for the operator to understand and which is excellent in operability can be provided.

In the first and second embodiments, the description has been given of the apparatus configuration in which the sample moving stage 1 is moved up and down along the optical axis. However, instead of this, a method in which the revolver is moved up and down is used. Alternatively, the effect is not impaired by other methods.

The focus adjusting mechanism of the color correction lens group can be variously changed without departing from the purpose of changing the focal length, such as a zoom method and a method of attaching and detaching a plurality of lenses. Further, although the autofocus described in the present embodiment belongs to the pupil division method among the active methods, it can be easily diverted to an autofocus device using another method without departing from the gist of the invention. It is possible.

[0052]

According to the first aspect of the present invention, when performing automatic focus detection, a wide range of focus determination range is ensured regardless of the depth of focus or the thickness of the sample depending on the magnification of each objective lens. While it is possible to perform the focusing operation to any optical axis direction position that the user wants to observe reliably and at high speed, the offset adjustment of the focus position is also possible.
Regardless of the objective lens magnification and the like, it is possible to easily and surely set all the samples that can be automatically focused with a sufficient adjustment width.

According to the second aspect of the present invention, in addition to the effects of the first aspect of the present invention, it is possible to perform the offset adjustment of the focus position, which is more excellent in operability.

According to the third aspect of the present invention, in addition to the effects of the first or second aspect of the present invention, when the position of the correction lens group reaches one of both ends of the driving range, this is immediately changed. Since recognition is possible, operability is further improved, and observation and the like can be performed more efficiently.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed circuit configuration of a control unit in FIG. 1;

FIG. 3 is a view showing an image forming state of spot light on a photodiode according to the embodiment.

FIG. 4 is a view showing characteristics of a signal from the photodetector according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sample moving stage 2 ... Revolver main body 3a, 3b ... Objective lens 4 ... Reference light source 5 ... Collimating lens 6 ... Projection side stopper 7 ... PBS 8 ... Condensing lens group 9 ... Color correction lens group 10 ... λ / 4 plate DESCRIPTION OF SYMBOLS 11 ... Diclock mirror 12 ... Light receiving side stopper 13 ... Condensing lens group 14 ... Photodiode (PD) 15 ... Revolver motor 16 ... Focusing motor 17 ... Color correction lens motor 18 ... Revolver motor drive part Reference Signs List 19: Focusing motor drive unit 20: Color correction lens motor drive unit 21: Revolving hole position detection unit 22: Light source drive unit 23: Amplifier 24: A / D converter 25: Control unit 26: Pulse counter 27: JOG encoder (E) 28 CPU main body 29 ROM 30 RAM 31 I / O port 32 Data bus 33 Limit detection unit ... observation sample

Claims (3)

[Claims] 1. An observation optical system for observing light from a sample by irradiating the sample with visible light through one of a plurality of interchangeable objective lenses, and the sample is passed through the objective lens in the observation optical system to the sample. A light source for projecting non-visible light, and disposed on an image plane of a light image of the non-visible light reflected by the sample,
A photoelectric converter for outputting a signal corresponding to the in-image position of the non-visible light, a focusing position adjusting means for adjusting a focusing position of the sample based on an output signal from the photoelectric converter, and An autofocus microscope including a correction unit that corrects a shift of non-visible light with respect to visible light by a correction lens group for each lens, wherein the correction unit adjusts a focal length of the correction lens group, A driving means for electrically driving the focal length adjusting mechanism according to the magnification of each of the objective lenses. 2. The correction means includes: a correction lens group moving mechanism capable of moving the correction lens group to an arbitrary position within a predetermined range in an optical axis direction; and an observer operating the correction lens group moving mechanism. An autofocus microscope comprising: a driving unit that is electrically driven by a signal from an input unit. 3. The information processing apparatus according to claim 1, wherein the correction means further includes a notification means for notifying when the position of the correction lens group reaches one of both ends of a driving range of the focal length adjusting mechanism. An autofocus microscope according to claim 1.