JP4097761B2 - Autofocus microscope and autofocus detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides an autofocus microscope capable of automatically adjusting the focus position of an observation sample.And automatic focus detection deviceAbout.
[0002]
[Prior art]
At present, microscopes capable of observing minute materials or recording observation images as video images are widely used for research in the biological field and inspection processes in the industrial field. When such a microscope is used, the focusing operation is usually performed by adjusting the focus of the observation sample by operating the focusing handle. However, since the operation is a manual operation, particularly when the focal depth is shallow and the focusing range is narrow like a high-magnification objective lens, considerable skill is required to quickly perform the focusing operation.
[0003]
If the operability of the focusing operation is poor, it will have an adverse effect on the operator's fatigue and a reduction in production efficiency. Particularly in routine work such as an inspection process, it is very important to perform this operation quickly to shorten the inspection time.
[0004]
Therefore, various microscopes having an automatic focusing function capable of automatically performing such a focusing operation have been proposed, and many proposals for improving them have been made.
[0005]
In Japanese Patent No. 2614843, the automatic focus detection position is corrected by correcting the wavelength difference between the infrared light for focus detection and the visible light actually observed, and the chromatic aberration of each objective lens when a plurality of objective lenses are used. Means for compensating for fluctuations are described, and improvement in operability and reduction in manufacturing costs are proposed.
[0006]
Also, Japanese Patent Laid-Open No. Hei 6-281409 has been proposed in order to detect a defect in each layer without any omission in a specimen having a step such as a semiconductor wafer formed in multiple layers.
[0007]
Furthermore, in Japanese Patent Laid-Open No. 8-43717, the optical path on the detection side is divided into two, and detection signals are obtained from different light receiving elements using two types of imaging lenses each having a different magnification. This is done in the area to improve the correspondence to the specimen.
[0008]
[Problems to be solved by the invention]
In the method proposed in the above-mentioned Patent No. 2614843, an adjustment unit is provided for each objective lens, and an offset value from the in-focus position can be set and reproduced for each objective lens, so that the chromatic aberration of the objective lens can be reproduced. The correction is sufficiently effective.
[0009]
However, no consideration is given to the positional deviation of the focal point due to variations in the specimen itself. This is effective for the focus position of one of the specimens with a step on the surface, such as a semiconductor wafer. Has the disadvantage of being out of focus. In this case, in order to observe the other in-focus position, the adjustment unit provided for each objective lens is operated to shift the optimum in-focus position for observation, or the automatic focus detection operation is temporarily interrupted, and the manual operation is performed manually. This results in being forced to focus on the camera.
[0010]
Japanese Patent Application Laid-Open No. 6-281409 describes an inspection apparatus for observing a plurality of focal positions, and is effective for complete routine inspection of a specific specimen. That is, it is an effective means for the inspection of a single specimen whose step on the multilayer surface is known in advance. However, there is a drawback that a rapid response cannot be taken when the shape of the sample changes, such as when observing another sample with different steps or when the thickness of the sample is unknown. In other words, in order to enable observation, it is necessary to change the focus offset value or newly register it, but no consideration has been given to the setting method, and in the worst case, the setting operation is performed with the observer. However, there may be other cases that must be done by a technician who is familiar with the equipment. Therefore, this method cannot be applied when a plurality of specimens must be observed.
[0011]
By the way, in this type of focus detection device, the range in which the focus position can be determined becomes narrower as the objective lens becomes higher in magnification due to its optical characteristics. This is because the imaging lens on the detection side has a fixed magnification. Therefore, in the two inventions disclosed in Japanese Patent No. 2614843 and Japanese Patent Laid-Open No. 6-281409, the offset and focal position of each objective lens are changed. Even if the correction is possible, the performance of the focus determination range, speed, accuracy, etc. will vary with the magnification of the optical system such as the objective lens.
[0012]
In addition, the above-mentioned JP-A-8-43717issueIn order to avoid the above-mentioned problem, the optical path on the detection side is divided into two parts and combined based on two types of detection signals from photoelectric conversion elements imaged using two types of imaging lenses each having a different magnification. A focus determination is performed. However, such a configuration inevitably increases the overall size of the apparatus and increases the price due to the increase in optical systems, light receiving elements, and the like. In addition, since each imaging lens is also a fixed magnification, an optimum focusing operation corresponding to various magnifications cannot be ensured.
[0013]
In addition, when performing focus offset by moving the position of the imaging lens on the detection side, the range of movement differs depending on whether the imaging lens has a low magnification or a high magnification, and the offset adjustment width is also limited. For this reason, there is a possibility that a satisfactory focus offset value cannot be set with the configuration explicitly disclosed in Japanese Patent Laid-Open No. Hei 6-281409.
[0014]
  The present invention has been made in view of the above circumstances, and its purpose is to always provide a wide range of focus determination range regardless of the magnification of the objective lens or the thickness of the specimen when performing automatic focus detection. While it is possible to focus and move to any position in the direction of the optical axis that the user wants to observe while ensuring it, it is always possible to adjust with a wide margin regardless of the magnification of the objective lens, etc. An easy-to-use autofocus microscope that can easily and reliably set the focus position offset for any autofocusable specimen.And automatic focus detection deviceIs to provide.
[0015]
[Means for Solving the Problems]
  The invention described in claim 1A plurality of replaceable objective lenses, an observation optical system for projecting illumination light onto the sample through one of the objective lenses, and observing light from the sample through the objective lens, and the observation lens through the objective lens. A detection light having a wavelength different from that of the illumination light is projected onto the sample, and a reflected light from the sample by the detection light is imaged through the objective lens, and reflected by the sample A photoelectric converter disposed on the image plane of the optical image by the detection light and outputting a signal corresponding to the position in the image plane of the reflected light, and a focus position of the sample based on an output signal from the photoelectric converter A focus position adjusting means for adjusting the position of the focus detection optical system, and a lens for correcting a deviation between the imaging position of the illumination light and the imaging position of the detection light via the objective lens. Correction means to correct by group The correction means comprises a focal length adjustment mechanism for adjusting the focal length of the correction lens group, and a drive means for driving the focal length adjustment mechanism in accordance with the magnification of each objective lens. .
[0016]
As a result of such a configuration, when performing automatic focus detection, regardless of the depth of focus or the thickness of the sample, which varies depending on the magnification of each objective lens, the user can observe any desired range while ensuring a wide focus determination range. While focusing on the optical axis position can be performed reliably and at high speed, it is always possible to adjust the offset of the focus position for any specimen that can be automatically focused regardless of the objective lens magnification, etc. It is possible to easily and reliably set with an adjustment width having a margin.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the overall configuration, and a plurality of objective lenses 3a and 3b, a revolver body 2 to which the plurality of objective lenses 3a and 3b can be attached, and the revolver body 2 are rotated so that an arbitrary objective lens 3 is passed through an optical path. An electric revolver from a revolver motor 15 that is electrically driven to be inserted therein, and a revolver position detector 21 for detecting which objective lens mounting position of the revolver body 2 is currently inserted in the optical path. Is configured.
[0021]
However, in this electric revolver, the revolver motor 15 is rotationally driven by the drive control of the revolver motor drive unit 18 that receives a signal from the control unit 25, and the objective lens 3 is mounted in any hole position of the revolver body 2. The contents detected by the rebo hole position detecting unit 21 for detecting whether or not it is sent are sent to the control unit 25 as they are.
[0022]
The control unit 25 is a well-known CPU circuit, as shown in FIG. 2, a CPU main body 28, a ROM 29 that stores a program for controlling the system, a RAM 30 that is a volatile memory that stores data necessary for control as needed, a control An I / O port 31 for inputting and outputting signals, a data bus 32 for connecting them, and a known peripheral circuit such as an oscillator and an address decoder (not shown). From 32, each peripheral device is controlled.
[0023]
An observation sample S to be observed is placed on the sample moving stage 1 and can be observed with the objective lens 3. The sample moving stage 1 is connected to a focusing motor 16 and can electrically move the sample moving stage 1 up and down in a direction perpendicular to the optical axis. The focusing motor 16 is driven by a focusing motor drive unit 19, and the focusing motor drive unit 19 is controlled by the control unit 25 via the I / O port 31.
[0024]
As the reference light source 4 used for autofocus, a light source in the visible light wavelength region such as infrared rays is used. The reference light source 4 is controlled by a light source driving unit 22 that performs pulse lighting of the light source and controls the intensity of the light source, and the laser light emitted from the reference light source 4 is a collimating lens 5 for maintaining parallel light. Then, only the P-polarized light component is reflected by the PBS 7 through the light-projecting-side stopper 6 that cuts half of the light beam and guided to the sample side. That is, the light beam once condensed by the condenser lens group 8 passes through the color correction lens group 9, is polarized by 45 ° when passing through the λ / 4 plate 10, and is reflected by the dichroic mirror 11.
[0025]
The color correction lens group 9 has both a zoom mechanism that changes the focal length by the color correction lens motor 17 and a mechanism that moves in the direction perpendicular to the optical axis. It is driven by the lens motor drive unit 20. Further, limit detection units 33 are provided at both ends of a predetermined range in the optical axis direction of the color correction lens group 9 to limit the movement range of the color correction lens group 9 in the optical axis direction.
[0026]
The dichroic mirror 11 has 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 is not shown here through the objective lens 3 in which visible light, that is, observation light and illumination light for inspecting the specimen is 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 reversed by 45 ° when passing through the λ / 4 plate 10 again through the objective lens 3 and the dichroic mirror 11 and switched to the S polarization component. Thereafter, the color correction lens group 9 and the condenser lens group 8 are returned to enter the PBS 7. Here, since the light beam is an S-polarized component as described above, it passes through the PBS 7 as it is, passes through the light receiving side stopper 12 and the condenser lens group 13, and then is a photodiode (hereinafter abbreviated as “PD”). 14 is imaged. 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 imaged at 14 is subjected to current / voltage conversion by the amplifier 23 and then amplified with a predetermined amplification factor, and then converted to a digital value by the A / D converter 24. The control unit 25 performs arithmetic processing.
[0027]
Further, as an operation unit that is directly operated by an object to be observed, an objective lens conversion SW (not shown) for rotating the revolver body 2 to change the objective lens 3 inserted in the optical path to one having an arbitrary magnification, autofocus An autofocus switch for setting / releasing the 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. Of these, the encoder signal of the JOG encoder 27 is provided. 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 how much the JOG encoder 27 is rotated in which direction, and moves each drive unit in accordance with the rotation amount of the JOG encoder 27. It is like that.
[0028]
Next, a case where the autofocus operation in the first embodiment is performed will be described. When an autofocus switch not shown in FIG. 1 is pressed, the control unit 25 gives a signal to the light source driving unit 22 in order to irradiate the observation sample S with a spot of infrared light for autofocusing. Start oscillation.
[0029]
A spot is irradiated on the observation sample S with a light beam from the reference light source 4, and the reflection is P.D. D. The actual autofocus control is performed according to the position of the projected spot.
[0030]
Here, the principle of the autofocus operation described in the present embodiment will be briefly described. If it is assumed that the position of the sample moving stage 1 is above the in-focus position, that is, close to the objective lens 3, the spot from the reference light source 4 is reflected quickly from the observation sample S. D. The spot image formed on the image 14 is formed as shown in FIG. 3A and closer to the sensor B from the center position and with a reduced intensity.
[0031]
On the contrary, when the sample moving stage 1 is below the in-focus position, that is, when it is far from the objective lens 3, the spot is imaged closer to the sensor A as shown in FIG.
[0032]
Further, as shown in FIG. 3B, the shape of the spot when the sample moving stage 1 is accurately at the in-focus position forms an image at substantially the center of the optical axis in a uniform range for both the sensors A and B. In addition, in this case, the light intensity at the center is the highest because of the focal position.
[0033]
While judging such movement and intensity of the spot, the control unit 25 calculates the following expression: {{A−B) / (A + B)} = 0
An autofocus operation is performed by moving the sample moving stage 1 to a point. 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, the surface of the observation sample 1 can be accurately focused.
[0034]
However, one big problem occurs here. That is, since the reference light source 4 that performs the autofocus operation is infrared light and has a wavelength different from that of the actual visible light, even if the autofocus device determines that the focus is in focus due to chromatic aberration, it is out of focus in the visible light region. Things happen. Therefore, the color correction lens group 9 is installed. The control unit 25 gives a drive instruction to the correction lens drive 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. 14 image forming positions are corrected. Since this correction movement amount can be limited to some extent by the characteristics of the objective lens 3 and the wavelength used for the reference light source 4, the correction movement value for each objective lens is preliminarily stored in the ROM 29 or other storage medium, for example, a non-volatile memory. By storing the data in an EEPROM or the like, correction work can be performed based on the data. Further, since this correction movement amount differs for each objective lens 3, it is stored for each objective lens 3 used.
[0035]
The color correction lens group 9 has another important role. Hereinafter, this role will be described.
Both the output signals of the sensors A and B from the photodetector input to the control unit 25 have characteristics as shown in FIG. 4A, and the signal processed by the control unit 25 is shown in FIG. 4B. The characteristics are as shown. That is, the shape of the signal differs greatly between when the high-magnification objective lens is attached and when the low-magnification objective lens is attached. The higher the magnification, the narrower the non-measurement surface displacement, that is, the signal appearing range in the vertical direction of the stage. . This is due to the difference in NA for each objective lens. The signal detected using a high-magnification objective lens with a large NA has a narrower distance between the peaks in each signal, and further increases and decreases sharply. Will be presented.
[0036]
In general, in-focus position detection devices determine the in-focus position using either one or both of the signals as shown in FIG. 4 (a) or FIG. 4 (b), so that these signals can be detected. If the range is narrow, it takes time to search the range, and as a result, it takes time to determine the focus.
[0037]
This problem can be avoided by providing the color correction lens group 9 with a zoom function as a focal length adjusting means. In other words, by reducing the focal length of the color correction lens group 9 for the low-magnification objective lens, and conversely increasing the focal length when the high-magnification objective lens is mounted, the shape of the detection signal due to the difference in NA between the objective lenses can be obtained. It is possible to eliminate the variation and always ensure a sufficient focus determination range. 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 above-described correction movement amount, so that the focal length correction value for each objective lens is stored in advance in the ROM 29 or other storage medium. For example, if the setting is made for each objective lens 3 used in an EEPROM or the like which is a nonvolatile memory, correction work based on the stored data can be performed. This completes focusing on the observed image.
[0038]
Therefore, before the autofocus operation is started in the present embodiment, the color correction lens group 9 performs correction based on the correction movement value and the focal length correction value corresponding to each mounted objective lens 3. It is assumed that an optimum autofocus operation environment corresponding to each objective lens 3 is set.
[0039]
With the color correction lens automatically adjusted as described above, 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.
[0040]
When 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 driving unit 22 and performs the data from the A / D converter 24 when performing the objective conversion operation. The acquisition and calculation processes are stopped, and the autofocus operation being executed is temporarily suspended. Then, the revolver motor drive unit 18 is driven, and the revolver motor 15 gives a rotation instruction to the revolver body 2. When the rotation of the revolver body 2 is completed and a new objective lens 3 is inserted into the optical path, the control unit 25 reads information from the rebo hole position detection unit 21 and the objective lens 3 currently inserted into the optical path is read. The magnification is confirmed, each correction value of the chromatic aberration correction lens group 9 corresponding to the magnification is read from the ROM 29 or a non-volatile memory (not shown), the correction lens drive unit 20 is driven according to the value, and the color correction lens motor 17 is rotated. After the focal length and position of the color correction lens group 9 are adjusted, the autofocus operation is restarted.
[0041]
Thus, according to the present embodiment, when automatic focus detection is performed, regardless of the magnification of the objective lens and the thickness of the sample, an arbitrary position (Z Direction) can be performed reliably and at high speed.
[0042]
(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. The autofocus operation itself is the same as that in the first embodiment, and the overall configuration is the same as in FIGS. 1 and 2, and the same parts are denoted by the same reference numerals. Illustration and description are omitted.
[0043]
However, consider the concern about whether or not the part that the operator actually wants to observe is in focus when the autofocus operation similar to that in the first embodiment described above is performed and the focusing is completed. That is, the spot diameter irradiated on the observation sample S is very small, and the spot does not always hit the site observed by the actual worker. Also, if there are many steps in the spot, D. In some cases, an accurate output cannot be obtained from 14. In order to solve this, in the present embodiment, the following operation is performed during the autofocus operation.
[0044]
During the autofocus operation, the control unit 25 controls the P.P. D. At the same time as the focus detection operation is performed by the input from 14, the data of the pulse counter 26 is read and the JOG encoder 27 is monitored. When the JOG encoder 27 generates a signal based on the rotation instruction, 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. As a result, when the color correction lens group 9 moves during the autofocus operation, it is natural that P.I. D. The spot shape to 14 changes. In response to this, the control unit 25 gives a driving signal to the focusing motor driving unit 19 and moves the sample moving stage 1. By repeatedly executing such an operation, an offset value is additionally set from the in-focus position detected by the apparatus as a result, and the operator can focus on the part that the operator wants to observe. Further, when the position of the color correction lens group 9 in the optical axis direction reaches either one of both ends of the range that is limited in advance by the offset operation by the operator, a signal is sent to the control unit 25 by the limit detection unit 33. In response to this, the control unit 25 uses a warning lamp, a buzzer, or the like of an operation unit (not shown) to notify the operator to that effect.
[0045]
The offset value determined by operating here, that is, the movement amount of the color correction lens group 9 in the optical axis direction is stored for each objective lens in the RAM 30 even after the objective lens is changed, and returned to the same objective lens. As described above, after changing the objective lens to a desired magnification, the color correction lens group 9 is moved to the corresponding offset value position, and then the autofocus operation is resumed. It is possible to make an observation that is always in focus at the position to be observed.
[0046]
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 amount of movement of the color correction lens during offset adjustment for each objective lens is very different. . For example, when it is desired to apply autofocus to a position shifted by 1 μm from the current focus position in a sample, the color correction lens may be moved in the order of μm for a low magnification objective lens, whereas for a high magnification objective lens, mm It may happen that an order movement amount is required. As a result, in the high magnification objective lens, it is considered 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.
[0047]
However, in the apparatus of the present embodiment, the color correction lens group 9 is provided with a focal length adjustment mechanism and is optimally adjusted for each magnification of the objective lens, so that the lens movement is always constant regardless of the type of objective lens. The offset operation can be performed by the amount. Therefore, the offset range is not dependent on the magnification of the objective lens, and if the movement range of the color correction lens group 9 is widened, an offset operation with a margin for any objective lens of any magnification is possible. It has become.
[0048]
However, since the amount of movement here is an offset value when it depends on the specimen and the observation location, it is the inherent offset value that is necessarily possessed by the apparatus itself due to chromatic aberration described in the first embodiment. I added that is basically different. Therefore, when storing data in the RAM 30, it is desirable to store and save them as separate data.
[0049]
Thus, according to this embodiment, autoFo-When adjusting the offset of the focus position during the focus operation, there is a means that can be set easily and reliably for any specimen that can be automatically focused with an adjustment range that always has a margin regardless of the magnification of the objective lens, etc. By adding the limit warning function in the offset operation, it is possible to provide a microscope that is easy for the operator to understand and excellent in operability. Even if the genus part is attached to both ends, the fiber can be surely inserted into the opening.
[0050]
In the first and second embodiments, the apparatus configuration in the case where the sample moving stage 1 is moved up and down along the optical axis has been described. However, instead of this, a method for moving the revolver up and down or other methods is used. Even if it is a system, the effect is not spoiled.
[0051]
In addition, the focus adjustment 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 or a method of attaching / detaching a plurality of lenses. Furthermore, the autofocus described in this embodiment belongs to the pupil division method among the active methods, but can easily be diverted to an autofocus device using another method without departing from the gist of the invention. Is possible.
[0052]
【The invention's effect】
According to the first aspect of the invention, when performing automatic focus detection, the user wants to observe while ensuring a wide focus determination range regardless of the depth of focus and the thickness of the sample, which differ depending on the magnification of each objective lens. While it is possible to perform focusing operation to any position in the optical axis direction reliably and at high speed, it is possible to adjust the focus position offset for any specimen that can be automatically focused regardless of the objective lens magnification, etc. Therefore, it is possible to set easily and reliably with an adjustment width always having a margin.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration according to a first embodiment of the present invention.
2 is a block diagram illustrating a detailed circuit configuration of a control unit in FIG. 1;
FIG. 3 is a diagram showing an image formation state of spot light on the photodiode according to the embodiment;
FIG. 4 is a view showing the characteristics of a signal from the photodetector according to the same embodiment.
[Explanation of symbols]
1 ... Sample moving stage
2 ... Revolver body
3a, 3b ... objective lens
4. Reference light source
5 ... Collimating lens
6 ... Light emission side stopper
7 ... PBS
8 ... Condensing lens group
9. Color correction lens group
10 ... λ / 4 plate
11 ... Dichroic mirror
12 ... Receiver side stopper
13 ... Condensing lens group
14 ... Photodiode (PD)
15 ... Revolver motor
16 ... Motor for focusing
17 ... Color correction lens motor
18 ... Revolver motor drive
19 ... Motor drive unit for focusing
20 ... Color correction lens motor drive unit
21 ... Rebo hole position detector
22: Light source drive unit
23 ... Amplifier
24 ... A / D converter
25 ... Control section
26: Pulse counter
27 ... JOG encoder (E)
28 ... CPU body
29 ... ROM
30 ... RAM
31 ... I / O port
32 ... Data bus
33 ... Limit detector
S: Observation sample

Claims (13)

Multiple interchangeable objective lenses;
An observation optical system for projecting illumination light onto the sample through one of the objective lenses, and observing light from the sample through the objective lens;
A focus detection optical system that projects detection light having a wavelength different from that of the illumination light to the sample through the objective lens, and forms an image of reflected light from the sample by the detection light through the objective lens;
A photoelectric converter disposed on the image plane of the optical image of the detection light reflected by the sample and outputting a signal corresponding to the position of the reflected light in the image plane;
Focusing position adjusting means for adjusting the focusing position of the sample based on an output signal from the photoelectric converter;
A correction unit that is disposed on the optical path of the focus detection optical system and corrects a deviation between the imaging position of the illumination light and the imaging position of the detection light through the objective lens by a correction lens group; ,
The correction unit includes an automatic focal length adjustment mechanism that adjusts a focal length of the correction lens group, and a drive unit that drives the focal length adjustment mechanism according to the magnification of each objective lens. Focus microscope.   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 the optical axis direction of the focus detection optical system, and an observer who uses the correction lens group moving mechanism. 2. The autofocus microscope according to claim 1, further comprising driving means for driving in accordance with a signal from an input unit to be operated. Multiple interchangeable objective lenses;
An observation optical system for projecting illumination light onto the sample through one of the objective lenses, and observing light from the sample through the objective lens;
A focus detection optical system that projects detection light having a wavelength different from that of the illumination light to the sample through the objective lens, and forms an image of reflected light from the sample by the detection light through the objective lens;
A photoelectric converter disposed on the image plane of the optical image of the detection light reflected by the sample and outputting a signal corresponding to the position of the reflected light in the image plane;
Focusing position adjusting means for adjusting the focusing position of the sample based on an output signal from the photoelectric converter;
A correction unit that is disposed on the optical path of the focus detection optical system and corrects a deviation between the imaging position of the illumination light and the imaging position of the detection light through the objective lens by a correction lens group; ,
The auto-focus microscope characterized in that the correction means comprises a focal length adjustment mechanism for adjusting the focal length of the correction lens group, and a drive means for driving the focal length adjustment mechanism.   4. The autofocus microscope according to claim 3, wherein the correction means adjusts the focal length of the correction lens group in accordance with the magnification or numerical aperture of each objective lens.   4. The autofocus microscope according to claim 3, wherein the correcting means adjusts a focal length of the lens group in accordance with a use wavelength of the detection light and the illumination light.   4. The autofocus microscope according to claim 3, wherein the correcting unit drives the driving unit in accordance with a signal from an input unit operated by an observer.   The correction means includes a correction lens group moving mechanism capable of moving the correction lens group to an arbitrary position along the optical axis direction of the focus detection optical system, and a driving means for driving the correction lens group moving mechanism. The autofocus microscope according to claim 3, wherein the autofocus microscope is provided. An observation optical system for projecting illumination light onto the sample through the objective lens, and observing light from the sample through the objective lens;
A focus detection optical system that projects detection light having a wavelength different from that of the illumination light to the sample through the objective lens, and forms an image of reflected light from the sample by the detection light through the objective lens;
A photoelectric converter disposed on the image plane of the optical image of the detection light reflected by the sample and outputting a signal corresponding to the position of the reflected light in the image plane;
Focusing position adjusting means for adjusting the focusing position of the sample based on an output signal from the photoelectric converter;
A correction lens group movable on the optical path of the focus detection optical system, and the imaging position of the observation optical system via the objective lens by moving the imaging position of the reflected light in the optical axis direction; An autofocus microscope comprising: a correction unit that adjusts an offset amount with respect to an imaging position of the focus detection optical system.   The correction means is responsive to a correction lens group moving mechanism capable of moving the correction lens group in the optical axis direction of the focus detection optical system, and a signal from an input unit for operating the correction lens group movement mechanism by an observer. 9. The autofocus microscope according to claim 8, further comprising driving means for driving the motor.   The correction unit includes a focal length adjustment mechanism that changes a focal length of the correction lens group, and a drive unit that drives the focal length adjustment mechanism according to a signal from an input unit operated by an observer. 9. The autofocus microscope according to claim 8, wherein 11. The autofocus microscope according to claim 8 , wherein the correction unit adjusts a focal length of the correction lens group in accordance with a magnification or a numerical aperture of each objective lens. An observation optical system that projects illumination light onto the sample through one of a plurality of interchangeable objective lenses and observes light from the sample, a stage for placing the sample, the sample, and the sample In an automatic focus detection apparatus used for a microscope having a focusing mechanism that adjusts a relative distance to an objective lens,
A light source that emits detection light having a wavelength different from that of the illumination light;
A focus detection optical system that irradiates the sample with detection light from the light source through the objective lens, and forms an image of reflected light from the sample by irradiation of the detection light through the objective lens;
A photoelectric converter disposed on the image plane of the optical image of the detection light reflected by the sample and outputting a signal corresponding to the position of the reflected light in the image plane;
Control means for outputting a control signal for driving the focusing mechanism based on an output signal from the photoelectric converter;
A correction unit that is disposed on the optical path of the focus detection optical system and corrects a deviation between the imaging position of the illumination light and the imaging position of the detection light through the objective lens by a correction lens group; ,
The automatic focus detection apparatus, wherein the correction means includes a focal length adjustment mechanism that adjusts a focal length of the correction lens group, and a drive means that drives the focal length adjustment mechanism. Illumination light is projected onto the sample through the objective lens, the observation optical system for observing the light from the sample, and detection light having a wavelength different from that of the illumination light is projected onto the sample through the objective lens, and the detection light A focus detection optical system that forms an image of the reflected light from the sample through the objective lens, a stage for placing the sample, and a focus for adjusting the relative distance between the sample and the objective lens In an automatic focus detection device used for a microscope having a mechanism,
A light source that emits detection light having a wavelength different from that of the illumination light;
A focus detection optical system that irradiates the sample with detection light from the light source through the objective lens, and forms an image of reflected light from the sample by irradiation of the detection light through the objective lens;
A photoelectric converter disposed on the image plane of the optical image of the detection light reflected by the sample and outputting a signal corresponding to the position of the reflected light in the image plane;
Control means for outputting a control signal for driving the focusing mechanism based on an output signal from the photoelectric converter;
It has a correction lens group that can move along the optical path of the focus detection optical system, and the imaging position of the reflected light is moved in the optical axis direction to form an image of the observation optical system via the objective lens. An automatic focus detection apparatus comprising: a correction unit that adjusts an offset amount between a position and an imaging position of the focus detection optical system.

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