JP5207213B2 - Autofocus device - Google Patents

Description

  The present invention relates to an autofocus device that obtains an in-focus state in which the focal point of an objective lens matches the observation object by adjusting the relative distance between the observation object and the objective lens.

  Generally, a passive method and an active method are known for autofocus for a microscope. The passive method obtains the optimum focus position from the contrast value of the image, but is not suitable for speeding up because control is performed through image processing. There are active methods as autofocus suitable for higher speeds, but these irradiate an observation object with laser light or the like, and obtain position information using information such as the position and shape of the return light. As a main method, there is a knife edge method as described in JP-A-2005-10665 and JP-A-2007-148161, but this method blocks half of the laser light irradiated on the objective lens. The position information of the object is obtained by changing the position of the return light according to the position of the object. Further, astigmatism methods as disclosed in Japanese Patent Application Laid-Open Nos. 2007-271978 and 2008-46327 are known. This is to know the position of the object by inserting a cylindrical lens in the optical path of the return light and measuring that the shape of the beam on the detector changes according to the position of the object.

  Further, as an autofocus using a displacement meter, one disclosed in Japanese Patent Laid-Open No. 5-323179 is known. In this example, a displacement meter is provided coaxially with the objective lens or at a different position to detect workpiece height information and perform autofocus.

JP 2005-10665 A JP 2007-148161 A JP 2007-271978 A JP 2008-046327 A JP H05-323179A

  However, since all of the above-described active object position detection methods obtain information through the objective lens, they only obtain information on a focal point in a very limited range in the optical axis direction. Therefore, in order to obtain the focus information of the target object, it is necessary to scan the object or the objective lens in the optical axis direction. In addition, once the above scanning is performed to find a target focal position and a tracking operation is performed on it, the area detected by these focal position detection methods is extremely small. There is a drawback that the position of the object cannot be detected stably only by a weak disturbance such as dust in this range. Furthermore, when trying to autofocus an object that has multiple surfaces in the direction of the optical axis, such as thin glass, depending on the scanning range, it may focus on a surface that is different from the surface that you want to focus on. is there. Furthermore, in these methods, since the detection accuracy of the focal position depends on the objective lens, the focus cannot be detected with high accuracy when a low-magnification objective lens is used.

  Also, the autofocus method using a displacement meter cannot be used for a well plate having an observation object beyond a thin glass simply by measuring the height of the object in a single order.

  An object of the present invention is to provide an autofocus device capable of obtaining a focused state with high accuracy and high speed.

The autofocus device of the present invention is an autofocus device that obtains an in-focus state in which the focus of the objective lens matches the observation object by adjusting the relative distance between the observation object and the objective lens. Measuring means for measuring by a triangulation method using a triangulation displacement meter, and control means for controlling the relative distance so as to obtain the in-focus state according to a measurement result by the measuring means , The measuring means measures the position of the back surface of the transparent body existing in front of the observation object as the measurement result, the control means controls the relative distance according to the measurement result by the measurement means, and The measurement position of the triangulation displacement meter and the focal point of the objective lens are offset in a direction perpendicular to the optical axis of the objective lens, and the transparent body has a plurality of wafers in an array. There is a well plate arranged offset amount of the offset, characterized in that it is an integral multiple of the distance between the wells in the well plate.
According to this autofocus device, the relative distance is measured by a triangulation method using a triangulation displacement meter, and the relative distance is controlled so that an in-focus state is obtained according to the measurement result. The in-focus state can be obtained.

Storage means for storing the measurement result of the well measured by the measurement means, and the well plate is relatively driven by the offset amount, so that the objective lens is a storage target in the storage means. Drive means for facing the well, and the control means controls the relative distance according to the measurement result stored in the storage means, thereby obtaining a focused state for the well. Good.

While the observation object is being observed by the objective lens for a specific well in the well plate, measurement by the measurement unit is performed in parallel with the observation in advance for a well offset from the specific well by the offset amount. And the storage means may store the measurement result.

The relative distance may be controlled in synchronism with the relative driving of the well plate by the offset amount.

The offset amount may be variable.

It may be possible to make the offset amount zero.

The triangulation displacement meter includes a light projecting optical system and a light receiving optical system, an bisector of an angle formed by an optical axis of the light projecting optical system and an optical axis of the light receiving optical system, and an optical axis of the objective lens And may be parallel.

The focal point of the objective lens in the focused state may be located within the measurement range of the triangulation displacement meter.

The triangulation displacement meter detects signals from the front surface and the back surface of the transparent body, and the measuring means determines the position of the back surface of the transparent body using these detected signals and the refractive index of the transparent body. You may measure.

You may provide the relative position detection means which detects the relative positional relationship of the said observation object and the focus of the said objective lens independently of the said measurement means.

The relative position detecting means may detect the relative position relationship based on an image photographed through the objective lens.

The relative position detecting means may detect the relative positional relationship using a laser beam projected through the objective lens.

Calibration means for calibrating the measuring means based on the relative positional relationship detected by the relative position detecting means may be provided.

The control means controls the relative distance so as to obtain the in-focus state by selectively using either the relative positional relationship detected by the relative position detecting means or the measurement result by the measuring means. May be.

Lens selection means for selecting a specific objective lens from the plurality of objective lenses, and retraction means for retracting the triangulation displacement meter from the objective lens when the objective lens is replaced by the selection means Good.

  According to the autofocus device of the present invention, the relative distance is measured by a triangulation method using a triangulation displacement meter, and the relative distance is controlled so that a focused state is obtained according to the measurement result. In addition, a focused state can be obtained at high speed.

  Embodiments of an autofocus device according to the present invention will be described below.

  The autofocus apparatus according to the present invention relates to autofocus of a microscope system, and is particularly suitable for a microscope system that observes a microscope image of a well plate having a large number of wells at high speed. However, the scope of application of the present invention is not limited to the above-described ones, and the present invention can also be applied to ordinary microscope systems and industrial microscope systems.

  Hereinafter, the autofocus device according to the first embodiment will be described with reference to FIGS.

  FIG. 1 is a block diagram showing the configuration of the autofocus device of this embodiment, and FIG. 2 is a perspective view showing the structure of a well plate.

  As shown in FIG. 2, the well plate 1 that accommodates the observation object is configured by arranging micro-containers called wells 1a into which cells are placed in an array, and the conditions such as each drug are changed. This makes it possible to conduct experiments efficiently. Further, the bottom surface of the well plate 1 is composed of a transparent glass plate 1b. As shown in FIG. 1, the well 1a can be observed from the lower surface by the objective lens 3 through the glass plate 1b.

  The well plate 1 can be moved by a XY table 2 in a plane perpendicular to the optical axis direction of the objective lens 3 (vertical direction in FIG. 1).

  The objective lens 3 can be finely moved in the optical axis direction (vertical direction in FIG. 1) by the Z stage 4, and the relative position with respect to the well plate 1 is variable. Further, the objective lens 3 is optically connected to a microscope barrel 5, and a high sensitivity camera 6 and a light source 7 for illuminating an observation object are connected to the microscope barrel 5.

  A dichroic mirror 8 is installed in the middle of the optical path connecting the objective lens 3 and the microscope barrel 5. The dichroic mirror 8 is configured to reflect a near-infrared laser that does not affect microscopic observation. Further, the dichroic mirror 8 is optically connected to the focus sensor 9.

  The focus sensor 9 emits a near-infrared laser and guides its return light to a detector by an optical system (not shown) to detect and output that the position and shape of the light change according to the positional relationship with the object. .

  Further, a triangulation displacement meter 10 is arranged in the vicinity of the objective lens 3.

  FIG. 3 is a perspective view showing the shape of the triangulation displacement meter 10.

  As shown in FIGS. 1 and 3, the triangulation displacement meter 10 includes a laser projecting unit 11 and a light receiving unit 12. Further, as shown in FIG. 1, the bisector of the angle formed by the optical axis 11a of the light projecting unit 11 and the optical axis 12a of the light receiving unit 12 and the optical axis of the objective lens 3 are substantially aligned. Yes. At this time, the objective lens 3 is arranged so that the focal point is within the measurement range of the triangulation displacement meter 10.

  As shown in FIG. 1, the XY table 2, the Z stage 4, the high-sensitivity camera 6, the focus sensor 9, and the light receiving unit 12 are connected to the controller 14 by control wiring indicated by dotted lines. In addition, a correspondence relationship between a position output of a triangulation displacement meter 10 and a position of the objective lens 3 described later is stored in the controller 14, and the controller 14 uses this correspondence relationship based on the signal of the triangulation displacement meter 10. Perform the focusing operation.

  The triangulation displacement meter 10 and the controller 14 are measurement means in the present invention, the focus sensor 9 and the controller 14 are relative position detection means in the present invention, and the controller 14 is control means, calibration means, and storage means in the present invention. Configure each.

  Next, the operation of the autofocus device of this embodiment will be described.

  FIG. 4 is a diagram showing the operating principle of the triangulation displacement meter 10.

  As shown in FIG. 4, the laser light from the laser light source 11 a of the light projecting unit 11 is irradiated to the object 20 through the light projecting optical system 11 b, and the light from the object 20 is received by the light receiving optical system 12 a of the light receiving unit 12. To the detector 12b. As shown by the solid line when the object 20 is near and by the dotted line when the object 20 is far, the imaging position on the detector 12b differs depending on the distance to the object 20, so the distance from the object 20 is The corresponding signal can be output.

  The spot diameter of a focus sensor through a conventional objective lens is on the order of microns, and the spot diameter is very small. On the other hand, the triangulation displacement meter 10 has a feature that it is resistant to disturbance because the spot diameter of the projected laser beam is as large as several tens of μm to several hundreds of μm.

  FIG. 5 is a diagram showing how the position of the well plate 1 is measured.

  The controller 14 drives the XY table 2 and positions one well 1 a in the well plate 1 below the optical axis of the objective lens 3. In this state, the triangulation displacement meter 10 measures the position of the well 1a.

  FIG. 6 is a diagram showing a position output obtained by the detector 12b during measurement.

  Since the bottom surface of the well 1a is composed of a glass plate 1b which is a thin glass plate (FIG. 5), the detector 12b (FIG. 4) of the triangulation displacement meter 10 causes the surface 1c of the glass plate 1b (see FIG. 6). Two position outputs are obtained, a large output from FIG. 5) and a small output from the back surface 1d of the glass plate 1b (FIG. 5). Among these, the position of the surface 1c can be accurately measured by the position output based on the surface 1c. However, since the light beam reflected from the back surface 1d passes through the inside of the glass plate 1b, correction is necessary to know the exact position of the back surface 1d.

  In the correction, the controller 14 corrects the refractive index by passing through the glass from the two outputs, calculates the thickness of the glass, and accurately calculates the back surface position of the glass. Specifically, two signals based on the front surface 1c and the back surface 1d, an angle formed by the optical axis 11a of the light projecting unit 11 and the glass plate 1b, an angle formed by the optical axis 12a of the light receiving unit 12 and the glass plate 1b, and glass The refractive index of the glass constituting the plate 1b is used to calculate the thickness of the glass plate 1b, and the accurate position of the back surface 11d is calculated from the position of the front surface 1c and the calculated thickness of the glass plate 1b.

  Thus, by using the triangulation displacement meter 10, the position of the back surface 1d of the glass plate 1b can be obtained without scanning the focal point of the objective lens 3 in the optical axis direction. In addition, unlike the method of passing through an objective lens, it is possible to always measure with high accuracy without depending on the magnification of the objective lens. Using this data, the controller 14 drives the Z stage 4 so that the focal point of the objective lens 3 comes to the position of the cell located several μm ahead of the back surface 1d of the glass plate 1b constituting the bottom surface of the well plate.

  In this state, the microscope light tube 5 irradiates light from the light source 7 to the cell to be observed through the objective lens 3, and highly sensitive light such as fluorescence from the cell through the dichroic mirror 8 or a filter (not shown). An image is formed on the camera 6. The controller 14 stores the focused image and drives the XY table 2 to move to the next well. By repeating this series of operations, a focused image for each well can be acquired at high speed.

  Further, the positional relationship between the triangulation displacement meter 10 and the objective lens 3 may be shifted due to the influence of thermal expansion due to long-term use. In such a case, even if the objective lens 3 is driven in accordance with a signal from the triangulation displacement meter 10, it may be impossible to focus. In this case, another focus sensor 9 is used. The focal point is focused on the glass surface of the well plate 1 by the signal of the focus sensor 9 and the position signal of the Z stage 4 at this time is stored in the controller 14, so that the signal of the triangulation displacement meter 10 and the objective lens 3 are again stored. Thus, the calibration operation of the triangulation displacement meter 10 is completed. The correspondence between the position output of the triangulation displacement meter 10 and the position of the objective lens 3 is updated by calibration and stored in the controller 14.

  Such a calibration operation does not need to be performed frequently. For example, the calibration may be performed every time several well plate measurements are performed. Some high-magnification objective lenses block the optical axis of the triangulation displacement meter 10 by the lens barrel body of the objective lens. In such a case, instead of focusing based on the triangulation displacement meter 10, focusing based on the focus sensor 9 can be used depending on the situation.

  In the above embodiment, the objective lens 3 is driven in the optical axis direction by the Z stage 4, but the well plate 1 may be moved instead of driving the objective lens 3. Further, the microscope is not limited to the fluorescence microscope, but may be bright field observation or phase difference observation. Further, a confocal microscope may be used as the microscope.

  Further, although the laser projection type focus sensor 9 has been described, the present invention is not limited to this, and for example, a focus signal may be extracted based on the luminance value of a microscope image.

  Further, when the position of the well plate is largely changed, a coarse movement stage that moves the objective lens 3 and the triangulation displacement meter 10 integrally in the optical axis direction of the objective lens may be added.

  As described above, according to the autofocus device of the present embodiment, the triangulation displacement meter is provided in the vicinity of the objective lens, and the focus is adjusted while always measuring the position of the well plate with the triangulation displacement meter. Alternatively, the position of the back surface of the glass on the bottom surface of the well plate can be measured without scanning the well plate in the optical axis direction, and the autofocus operation can be performed at high speed. In addition, since the spot diameter for irradiating the laser beam is large, it is possible to provide autofocus that is more resistant to disturbance than in the past. Furthermore, the focus position can always be adjusted with high accuracy without depending on the magnification of the objective lens. For example, even a low-magnification objective lens can realize high-precision autofocus.

  In addition, since the bisector of the angle formed by the optical axis of the projection optical system and the optical axis of the light receiving optical system of the triangulation displacement meter and the optical axis of the objective lens are substantially matched, measurement by the triangulation displacement meter The position and the observation position of the objective lens can be configured at the same position, and accurate autofocus is possible. In addition, since the light from the light projecting optical system is regularly reflected by the well plate and enters the light receiving optical system, the detection signal is large and stable measurement is possible.

  In addition, since the focus of the objective lens is positioned within the measurement range of the triangulation displacement meter, the focus of the objective lens can be adjusted while measuring the position of the well plate with the triangulation displacement meter. Autofocus is possible with accuracy.

  In addition, the triangulation displacement meter detects signals from the glass surface on the bottom of the well plate and signals from the back surface, and uses these signals and the refractive index of the glass to calculate the position of the back surface of the transparent body. Therefore, the position of the back surface can be obtained more accurately. Thus, even when the object is observed through a transparent body, stable alignment is possible.

  Further, in addition to the triangulation displacement meter, a focus sensor 9 for determining the relative positional relationship between the well plate and the focal point of the objective lens is provided separately. Therefore, depending on the characteristics of the objective lens and the like, the measurement result of the triangulation displacement meter or Any of the measurement results of the focus sensor 9 can be selectively used. In addition, it is possible to calibrate the triangulation displacement meter signal and the focal position of the objective lens using the signal of the focus sensor 9.

  Hereinafter, with respect to the autofocus device according to the second embodiment, differences from the first embodiment will be described with reference to FIG. In this embodiment, an example in which the measurement position by the triangulation displacement meter 10 is offset from the optical axis of the objective lens is shown. In FIG. 7, the same elements as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, the description of the same components as those in the first embodiment is omitted.

  FIG. 7 is a plan view of the objective lens 3 and the triangulation displacement meter 10 when the well plate direction is viewed from the microscope barrel direction. The well plate 1A shown in FIG. 7 has 96 holes, has a layout in which wells W1 to W96 are arranged in 12 rows in the horizontal direction and 8 rows in the vertical direction, and the pitch between the wells W1 to W96 is 9 mm. .

  On the other hand, as shown in FIG. 7, the optical axis center 3a of the objective lens 3 and the measurement point 10a of the triangulation displacement meter 10 are offset by L. Here, L is equal to a pitch of 9 mm between the wells W1 to W96. Further, the bisector of the angle formed by the optical axis 11 a and the optical axis 12 a is parallel to the optical axis 3 a of the objective lens 3 in the vertical plane formed by the optical axis 11 a and the optical axis 12 a of the light projecting unit 11 and the light receiving unit 12. It is comprised so that it may become a proper positional relationship. Further, in the triangulation displacement meter 10, the offset amount with respect to the optical axis 3 a of the objective lens 3 is variable in the direction of the arrow P by the moving stage 13.

  At the time of observation, as shown in FIG. 7, the well plate 1 is sequentially moved in the direction of the arrow Q by the XY table 2 (FIG. 1) to start observation from the upper left well W1 in FIG. The observation target is switched to the right well W2, well W3,.

  First, the bottom surface of the well W <b> 1 is positioned on the observation position 10 a of the triangulation displacement meter 10. Here, the triangulation displacement meter 10 measures the positions of the front and back surfaces of the glass on the bottom surface of the well W1 in the same manner as in the first embodiment, and stores the measured values in the controller 14.

  Further, the well plate 1 is moved to the left by the pitch L, and at the same time, the objective lens 3 is driven by the Z stage 4 based on the measurement value stored in the controller 14 to focus.

  Here, the objective lens 3 is focused on the cells in the well W1 to capture an image, and at the same time, the triangulation displacement meter 10 simultaneously measures the bottom surface of the next well W2 and stores the measured value in the controller 14. Next, at the same time as the well plate 1 is driven by one pitch, the objective lens 3 is focused on the cells in the well W2. At the same time that an image is taken in this state, the triangulation displacement meter 10 simultaneously measures the bottom surface of the next well W3 and stores the measured value in the controller 14. By sequentially repeating such operations, the focus operation and the observation operation of the wells W1 to W12 for one row of the well plate are performed. After the observation of the first row is completed, the well moves down one row, and focus and observation are started again from the well W13 in the left direction. In this way, one well plate is observed.

  In the present embodiment, an example in which L is 9 mm is shown, but the present invention is not limited to this, and L may be a multiple of 9 mm. Further, L may be a multiple of 4.5 mm, which is the pitch between wells, corresponding to a well plate having a fine pitch of 384 holes. Further, L may be a multiple of 2.25 mm, which is a pitch between wells, corresponding to a well plate having a fine pitch of 1,526 holes.

  Further, since the optical axis of the triangulation displacement meter 10 may be blocked depending on the objective lens, the triangulation displacement meter 10 may be moved so that the stage 13 is driven and the optimum L is obtained. Further, the stage 13 may be driven to move the measurement point of the triangulation displacement meter 10 on the optical axis of the objective lens 3 as in the first embodiment.

  Also in this embodiment, it is preferable to perform the calibration operation of the triangulation displacement meter 10 using a focus sensor similar to or in place of the focus sensor 9 of the first embodiment. When this operation is performed, in consideration of the fact that there is an offset in addition to the operation of the first embodiment, calibration can be realized with high accuracy by performing calibration using the corresponding position data. That is, for example, after measurement by the triangulation displacement meter 10, the measurement object may be moved by the offset amount L and measured by the focus sensor so that the measurement values at the same position can be compared.

  As described above, the autofocus device according to the second embodiment is configured such that the measurement position of the displacement meter and the focus of the objective lens are offset, and the offset amount is an integral multiple of the distance between wells. Since the displacement meter measures the position information of the well to be observed in advance, and the objective lens is moved using the measurement signal simultaneously with the movement of the well, autofocus can be performed at a very high speed.

  In addition, since the bisector of the angle formed by the optical axis of the light projecting optical system and the optical axis of the light receiving optical system is substantially parallel to the optical axis of the objective lens, the light from the light projecting optical system is almost totally reflected by the well. Then, since it enters the light receiving optical system, the signal intensity is increased and stable measurement can be performed.

  In addition, since the measurement position of the displacement meter and the amount by which the focal point of the objective lens is offset are variably configured, an optimum configuration can be obtained according to the situation of the objective lens and the well plate.

  In addition, the autofocus device according to the second embodiment has the same advantages as the first embodiment.

  Hereinafter, the autofocus device according to the third embodiment will be described with reference to FIG. This embodiment shows an example in which the autofocus device of Embodiment 2 has a plurality of objective lenses. In FIG. 8, the same elements as those of the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, the description of the same components as those in the second embodiment is omitted.

  FIG. 8 shows a configuration in the vicinity of the objective lens viewed from the well plate side.

  As shown in FIG. 8, a cross-shaped revolver 30 on which four objective lenses 31, 32, 33, 34 are mounted is attached to a rotation shaft 35 so as to be rotatable. Here, when exchanging the objective lens, the displacement sensor is retracted in the S direction by the moving stage 13, and then the revolver 30 is rotated in the R direction by a rotary actuator (not shown). This has the effect that a plurality of objective lenses can be used.

  Here, the rotation axis 35 and the optical axis of the objective lens under observation may be parallel, but preferably the rotation axis 35 forms an angle of about 10 degrees with respect to the optical axis, and an objective other than the objective lens 31 under observation is present. It is desirable that the lens has a general microscope revolver configuration that is separated from the well plate.

  Hereinafter, the autofocus device according to the fourth embodiment will be described with reference to FIG. In this embodiment, the objective lens replacement method is a linear movement with respect to the autofocus device of the third embodiment. An example having a plurality of objective lenses is shown. In FIG. 8, the same elements as those of the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, the description of the same components as those in the second embodiment is omitted.

  FIG. 9 is a view from the well plate side. The objective lenses 35, 36, and 37 are linearly arranged on the objective lens base 38 and can be moved in the T direction by the moving stage 39. When exchanging the objective lens, the displacement meter 10 is retracted in the U direction by the moving stage 13. FIG. 9 shows a state where the objective lens 36 is used.

  The arrangement method of the objective lenses is not limited to the linear arrangement as shown in FIG. 9, but the objective lenses 35, 36, and 37 are arranged on the arc-like objective table 40 as shown in FIG. You may exchange by moving. FIG. 10 shows a state where the objective lens 36 is used.

  As described above, according to the autofocus device of the present invention, the relative distance is measured by a triangulation method using a triangulation displacement meter, and the in-focus state is obtained according to the measurement result. Since the control is performed, the in-focus state can be obtained with high accuracy and high speed.

  The scope of application of the present invention is not limited to the above embodiment. The present invention can be widely applied to an autofocus device that obtains an in-focus state in which the focus of the objective lens matches the observation object by adjusting the relative distance between the observation object and the objective lens.

1 is a block diagram illustrating a configuration of an autofocus device according to Embodiment 1. FIG. The perspective view which shows the structure of a well plate. The perspective view which shows the shape of a triangulation displacement meter. The figure which shows the principle of operation of a triangulation displacement meter. The figure which shows a mode that the position of a well plate is measured. The figure which shows the position output obtained by a detector at the time of a measurement. FIG. 6 is a plan view illustrating an autofocus device according to a second embodiment. FIG. 6 is a diagram illustrating an autofocus device according to a third embodiment. FIG. 6 is a diagram illustrating an autofocus device according to a fourth embodiment. The figure which shows the example moved to an objective lens circular arc direction.

Explanation of symbols

9 Focus sensor (relative position detection means)
10 Triangulation displacement meter (measuring means)
14 Controller (Measurement means, relative position detection means, calibration means)

Claims (15)

In an autofocus device that obtains a focused state in which the focus of the objective lens matches the observation object by adjusting the relative distance between the observation object and the objective lens,
Measuring means for measuring the relative distance by a triangulation method using a triangulation displacement meter,
Control means for controlling the relative distance so as to obtain the in-focus state according to the measurement result by the measurement means;
Equipped with a,
The measuring means measures the position of the back surface of the transparent body present in front of the observation object as the measurement result,
The control means controls the relative distance according to the measurement result by the measurement means,
The measurement position of the triangulation displacement meter and the focal point of the objective lens are offset in a direction perpendicular to the optical axis of the objective lens,
The auto-focus device, wherein the transparent body is a well plate in which a plurality of wells are arranged in an array, and the offset amount of the offset is an integral multiple of the distance between the wells in the well plate .   Storage means for storing the measurement result of the well measured by the measurement means;
  Driving means for relatively driving the well plate by the offset amount so that the objective lens faces the well to be stored in the storage means;
With
  2. The autofocus device according to claim 1, wherein the control unit obtains a focused state for the well by controlling the relative distance in accordance with the measurement result stored in the storage unit. 3. .   While the observation object is being observed by the objective lens for a specific well in the well plate, measurement by the measurement unit is performed in parallel with the observation in advance for a well offset from the specific well by the offset amount. And run
  The autofocus apparatus according to claim 2, wherein the storage unit stores the measurement result.   4. The autofocus device according to claim 3, wherein the relative distance is controlled in synchronization with the drive for relatively driving the well plate by the offset amount.   The autofocus device according to any one of claims 1 to 4, wherein the offset amount is variable.   The autofocus device according to claim 5, wherein the offset amount can be zero. The triangulation displacement meter includes a light projecting optical system and a light receiving optical system,
  7. The bisector of the angle formed by the optical axis of the light projecting optical system and the optical axis of the light receiving optical system and the optical axis of the objective lens are parallel to each other. The autofocus device according to claim 1. The autofocus device according to any one of claims 1 to 7, wherein a focal point of the objective lens in the focused state is located within a measurement range of the triangulation displacement meter. The triangulation displacement meter detects signals from the front surface and the back surface of the transparent body, and the measuring means determines the position of the back surface of the transparent body using these detected signals and the refractive index of the transparent body. The autofocus device according to claim 1, wherein measurement is performed. The autofocus according to any one of claims 1 to 9, further comprising a relative position detection unit that detects a relative positional relationship between the observation object and the focal point of the objective lens independently of the measurement unit. apparatus. 11. The autofocus device according to claim 10, wherein the relative position detecting unit detects the relative positional relationship based on an image photographed through the objective lens. 12. The autofocus device according to claim 11, wherein the relative position detecting unit detects the relative positional relationship using a laser beam projected through the objective lens. The autofocus device according to claim 10, further comprising a calibration unit that calibrates the measurement unit based on the relative positional relationship detected by the relative position detection unit. The control means controls the relative distance so as to obtain the in-focus state by selectively using either the relative positional relationship detected by the relative position detecting means or the measurement result by the measuring means. The autofocus device according to any one of claims 10 to 13, wherein Lens selecting means for selecting a specific objective lens from the plurality of objective lenses;
  Retreating means for retracting the triangulation displacement meter from the objective lens when the objective lens is replaced by the selection means;
The autofocus device according to claim 1, further comprising:

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