JPH0580247A - Microscope equipped with automatic focusing device - Google Patents

Abstract

PURPOSE:To perform automatic focusing in a short time. CONSTITUTION:A stage 72 is driven in the direction of an optical path through a stage driving part 72 until a CPU detects a focusing position based on the image pickup data of an image pickup element for focusing. The reference position 144 of the stage 73 is set slightly below the logical focus position of an objective 140. Position sensors 145 and 146, and 147 are installed at the upper-limit position 141 and lower-limit position 142 of the movement range of the stage 73, and the reference position 144. The stage 73 is moved to the reference position 144 at the time of focusing and moved up at every interval of 100mum, it is decided whether the image pickup data is focusing position or not, and the stage 73 is stopped at the focusing position.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a microscope with an autofocus device.

[0002]

2. Description of the Related Art As an automatic focusing device in a conventional microscope, a method of focusing by measuring the distance between the objective lens and the sample surface with a laser beam or the like, or air is blown from the tip of the objective lens toward the sample surface. A method is known in which the distance is measured by the pressure change and the focus is adjusted. However, in these methods, especially in the case of a biological microscope, for example, a deviation of the focusing position occurs due to variations in the thickness of the cover glass, etc., which makes accurate focusing difficult, and also due to the difference in parfocality of the objective lens. Variation is also a problem.

Further, in the case of a microscope using an image pickup device, after the conditions are set by a complicated microscope operation, the focusing can be performed only when the conditions required for the image pickup device are satisfied. Was unsuitable for. Also, when taking a picture with a microscope using a low-magnification objective lens, the depth of field on the object side is so deep that observing through an eyepiece causes focus adjustment regardless of where the focus is. Due to the action, the image is observed to be in focus, and on the other hand, there is a drawback that good focusing cannot be performed on the film surface because the depth of focus is shallow on the image side.

[0004]

Further, when the automatic focus adjustment of the microscope is performed, the stage is moved up and down based on the amount of light obtained by the image pickup device, and the focus position is detected and stopped. However, the conventional apparatus has a drawback that it takes time to bring the stage to the in-focus position because the stage at an arbitrary position is simply moved up and down according to the amount of light received by the image sensor. In addition, depending on the driving speed of the stage, an overrun occurs, so that the stage must be moved back and forth near the in-focus position, and it was difficult to accurately stop the stage at the in-focus position in a short time.

In view of such problems, it is an object of the present invention to provide a microscope equipped with an automatic focusing device which can move and stop the stage to a focusing position quickly and accurately during automatic focusing. To do.

[0006]

A microscope equipped with an autofocus device according to the present invention moves a stage up and down by a focusing drive unit based on the amount of light received by an image pickup device, and stops the stage at a focus position. In a microscope equipped with such an autofocus device, means for setting and storing as a reference position a position slightly displaced from the theoretical focusing position with respect to the objective lens in the optical path direction, and the stage at the reference position during focus adjustment. A reference position moving unit for moving the stage, a unit for moving the stage in a theoretical focusing position direction at predetermined intervals from the reference position, and a stage stopping unit for stopping the stage at the focusing position. To do.

[0007]

When the focus is adjusted, the stage is moved to the reference position, and the stage is moved in the theoretical focusing position direction of the objective lens at predetermined intervals based on the image pickup data obtained by the image pickup device. Stops the stage at the position where the focus position is detected.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The outline of the present invention will be described below with reference to the drawings. FIG. 1 shows an optical system of a microscope which is the basis of the present invention. 1 is a light source such as a halogen lamp, 2 is a collector lens, 3 is a plurality of light sources for dimming without changing the color temperature of the light source 1. ND filter unit consisting of the ND filter, 4 is a field stop, 5 is an aperture stop, and 6 is a plurality of units 6a, 6b, 6 that can be selectively inserted in the optical path.
Condenser lens composed of c, 7 is a stage, and 8 are units 8a, 8b, 8 attached to a revolver 9, respectively.
The objective lens composed of c is a beam splitter which is detachably arranged in the optical path so as to switch the optical path to an observation system or a photography system, 12 is an eyepiece optical system, and 13 is a photography. A photo-taking lens composed of a plurality of units 13a, 13b, 13c that can be selectively inserted into the optical path for use, 14 is a photo-sensing light-receiving element 15 through a slit for removing harmful light such as an imaging lens and flare for taking a picture. A beam splitter 16 that splits the light amount at a fixed ratio to the camera 1 through an imaging lens and a camera shutter 17
A beam splitter that splits the amount of light to the image sensor 19 for focus detection on the film surface of 8 and another imaging lens, and 20 is a beam splitting chopper for automatic focusing.

Next, FIG. 2 shows a block diagram of a control system of a microscope having the optical system of FIG. Reference numeral 21 is an image pickup signal processing circuit for controlling the focus detection image pickup element 19 and processing an output signal thereof, 22 is a drive circuit for driving the shutter 17 and film winding of the camera 18 during photography, and 23 is a light receiving element 15 A photometry circuit for performing direct photometry by the output from the device, a switching drive unit 24 for selecting the magnification of the taking lens 13, and a beam splitter 1
Optical path switching drive unit for inserting / removing 0 and 11; 26, switching drive unit for switching the objective lens 8; 27, focusing drive unit for vertically moving the stage 7; 28, condenser lens 6;
A switching drive unit for switching between the aperture stop 5 and the field stop 4, and 30 an ND filter 3.
A switching drive unit 31 for selectively switching the light source 1 and a light source device 31 for dimming the light source 1. Here, each of the drive units 24 to 30 is configured so as to be able to simultaneously detect the switching state, the control state, and the like. Reference numeral 32 is a CPU, 33 is an automatic exposure calculation control unit including a microcomputer, 34 is a shooting operation display unit including operation buttons such as film data or a release necessary for photographing, 35 is objective lens data, film data, for automatic focusing A storage unit for storing data and the like, which is backed up by a battery as necessary. An operation display unit 36 includes operation switches necessary for each drive unit, automatic focusing switches, operation switches necessary for the objective lens data set, and the like.

The operation of the microscope thus constructed will be described below. When power is turned on first, CP
U32 receives a signal relating to the objective lens 8 inserted in the optical path from the objective lens switching drive unit 26, reads the magnification and type (numerical aperture) of the objective lens from the storage unit 35, and based on these data. A proper condenser lens 6 is selected, and the condenser lens 6 is switched through the condenser lens switching drive unit 28. At the same time, an appropriate aperture diameter of the aperture diaphragm 5 and the field diaphragm 4 is calculated, and the aperture diameter is supplied via the diaphragm control drive unit. Set. Further, the CPU 32 selects a combination of the light amount of the light source 1 and the ND filter 3 based on the read objective lens data, and sets it to a predetermined standard brightness via the light source device 31 and the ND filter switching driving unit 30. Thus, the illumination light can be automatically set to the standard state when the power is turned on. Further, even when the objective lens, the taking lens, etc. are switched, the switching information of these is input to the CPU 32, and the automatic setting can be similarly performed. Further, the film data (ASA value, etc.) of the camera is stored in the storage unit 35, and at the same time when the power is turned on, the data of the film ready to be photographed is read from the storage unit 35 and calculated by the automatic exposure calculation control unit 33. Then, the image is displayed on the photographing operation display unit 34 and the exposure is determined. On the other hand, when the image pickup signal from the focus detection image pickup device 19 is input to the CPU 32, the CPU 32 calculates and determines the in-focus state from the image pickup signal based on the objective lens data in the optical path at that time, and sets the focus drive unit 27. The stage 7 is driven via this, and thus automatic focusing is performed.

The above is the outline of the present invention. Next, one embodiment of the present invention will be described in detail with reference to the drawings. Figure 3
Shows a control device 50 of the microscope according to the present invention.
1 is a CPU, 52 is a RAM backed up by a battery 53 when the power is cut off, 54 is a ROM as a program memory, 55 is an arithmetic unit used for arithmetic accuracy and time reduction, and 56 is an external control of the control device 50. From the external control device 57, 58 is an interface for the photographing device 59, 60 is an I / O for exchanging data and signals between the CPU 51 and all the drive units such as optical path switching and revolver.
It is a port. 61 is an image sensor using a one-dimensional image sensor for automatic focusing, and 62 is an image sensor 61.
Drive and imaging signal processing circuit, and 63 is an A / D converter. Reference numeral 64 denotes an operation panel including operation switches and a display, which inputs / outputs signals relating to the objective lens, switching signals to each drive unit, and the like via the interface 65.
Input and output to the port 60.

Reference numeral 66 is a drive unit for switching the taking lens 67, and 68 is a drive unit for a beam splitter 69 for switching the optical path between the observation system and the photographic system. At the same time, it is detected which optical path the optical path is and the detection signal is output. It can be output to the CPU 51.
Reference numeral 70 denotes an objective lens switching driving unit that rotationally drives the revolver 71, and can simultaneously detect the position of the revolver 71, that is, the objective lens inserted in the optical path. 72 is stage 7
A focusing stage drive unit for moving the lens 3 up and down for focusing, a switching drive unit 74 for switching the condenser lens 75 according to the magnification of the objective lens, a control drive unit 76 for controlling the aperture diameter of the aperture stop 77, and a reference numeral 78. Is a control drive unit for controlling the aperture diameter of the field stop 79, 80 is a switching drive unit for switching the ND filter unit 81 used for dimming to adjust the transmitted light amount ratio, and 82 is for dimming the light source 83. A dimming circuit, 84 is a drive for a pupil splitting chopper 85 used for automatic focusing.

FIG. 4 shows an example of the operation panel 64, where 86 is the operation panel, 87 is a switch for inputting the magnification and type (SPLAN, SPLAN APO, DPLAN, etc.) of the objective lens, and 88 is the objective lens. Magnification indicator, 89 is an objective lens type indicator, 90 is a switch for switching the optical path to an observation system, a photographic optical system, etc., 91 is an indicator indicating the type of the optical path switched to the use state, 92, Reference numeral 93 is a switch for manually adjusting the field stop 79 and the aperture stop 77 to an appropriate stop diameter, 94 is a switch for dimming,
Reference numeral 95 is a magnification switching switch of the taking lens 67, 96 is a magnification display of the taking lens, 97 is a switch for driving the focusing stage, 98 is a revolver activation switch, and 99 is an automatic focusing activation switch.

This embodiment is constructed as described above,
First, the data set of the objective lens and its related operation will be described. Here, as an example, the revolver 71
In the case where the objective lens SPLAN 10 × is switched and inserted in the optical path of, the magnification is 10 ×, the type SPLAN is set by the switch 87 on the operation panel 86.
Is selected and set and input, this information is input to the CPU 51 through the interface 65 and the I / O port 60. The CPU 51 reads out the objective lens position on the optical path of the revolver 71 by the objective lens switching drive unit 70,
The objective data table 100 (FIG. 5) is created from the revolver position and the information from the operation panel 86, and the RAM is created.
52. This objective data table 100 is
Including the magnification and type of the objective lens corresponding to the revolver position data, in the case of FIG. 5, the objective data table 100 is created for the six revolver positions.

The CPU 51 constantly monitors the objective data table 100 to perform the next calculation and control. That is, the CPU 51 determines the magnification of the condenser lens 75 from the table of FIG. 6 according to the objective data table 100, outputs the switching data to the condenser lens switching drive unit 74, and switches to an appropriate condenser lens.
Here, the condenser lens 70 is switched in three stages depending on the magnification of the objective lens. After that, the aperture diameters of the field stop 79 and the aperture stop 77 are determined from the objective data table 100 in order to set the best observation condition.
First, how to determine the aperture diameter of the field stop 79 will be described. The diaphragm diameter d ₁ of the field diaphragm is calculated by the following equation. d ₁ = [FNo. (field number) / (objective lens magnification × FS projection magnification)] × K1 ... where FNo. (field number) is the optical path as shown in the table of FIG. It is determined by the magnification of the taking lens 67 in the optical path of the observation system (Bi) or the photography system (FK), and the FS projection magnification is determined by the magnification of the condenser lens 75 as shown in the table of FIG. .. Further, K1 is the ratio to the visual field, and if K1 = 1, the value d ₁ calculated by the equation gives the diaphragm diameter circumscribing the visual field,
When the data set and at power-on of the objective lens in the present embodiment is adapted to stop diameter d ₁ of the field stop 79 is determined as K1 = 1, therefore it is an optical path observation system in photography system Even if there is, the field diaphragm is always set to the diaphragm diameter d ₁ circumscribing the field according to the formula.

Next, the aperture diameter d of the aperture stop 77.₂Is
Is calculated. d₂= NA × 2 × f × K2 ... where NA is the objective lens as shown in the table of FIG.
Similarly, the aperture value f determined by the magnification and type of
Focus of condenser lens 75 required from the table
It is a distance. K2 is the ratio to the pupil diameter, and K2 = 1
Then the value d obtained from the formula₂Is an aperture of 100% of the pupil diameter
The diameter is given, but in this embodiment the objective lens data set
At the time of turning on the power and K2 = 0.8, the aperture stop 77
Aperture diameter d ₂Of the objective lens that is most suitable for observation
The initial setting is 80% of the diameter. The figure
6 and the table of FIG. 7 are stored in the ROM 54.
Here, the objective lens is SPLAN 10 × and the optical path is the observation system.
If, then each aperture diameter is automatically set d₁, D₂Is the following
Is calculated as follows. From the tables of FIGS. 6 and 7, FN
o. = 28, FS projection magnification = 0.133, and K
If 1 = 1, then d₁= [28 / (10 × 0.133)] × 1≈21.1 (mm), and similarly, from the table of FIG. 6, NA = 0.3,
If f = 12 is obtained, and if K2 = 0.8, then
Et d₂= 0.3 × 2 × 12 × 0.8≈5.8 (mm) is obtained.

The above calculation is performed by the CPU 51 and the calculator 55, and depending on the calculation result, the field stop 7 is driven via the field stop control drive unit 78 and the aperture stop control drive unit 76.
9 and the aperture stop 77 are set to the stop diameters d ₁ and d ₂ . FIG. 8 is a block diagram showing the control of the field stop 79 or the aperture stop 77, 110 is a D / A converter, 111,
Reference numeral 112 is an amplifier, 113 is a motor drive circuit, 114 is a motor, 115 is an aperture mechanism opened and closed by the moder 114 via a gear, and 116 is a potentiometer that detects the position of the aperture mechanism 115 by the gear. The aperture diameter calculated as described above is digitally converted. When 8-bit digital conversion is performed here, the aperture diameter range is 0 to 0.
Assuming 34 mm, D / A data = field stop diameter × 7.5 ∴D / A data = [F No. (field number) / (objective lens magnification × FS projection magnification)] × K1 × 7.5 ... Therefore, the resolution is 0.13 mm / bit.

The data digitally converted to 8 bits is C
D / A converter 1 from PU 51 via I / O port 60
The signal is input to 10, where it is converted into an analog signal, amplified by an amplifier 111, and a motor drive circuit 113 drives a motor 114. Therefore, the diaphragm mechanism 115 can be opened and closed, but since its position is constantly monitored by the potentiometer 116 and fed back to the amplifier 111 via the amplifier 112, it can be controlled to a predetermined diaphragm diameter.

Next, the automatic setting operation for setting the optimum brightness for observation when setting the objective lens data will be described. The illuminance L of the observation light on the image plane is expressed as follows. L = LA × ND × AS × Ob × Bi (lx) ... Here, ND is, for example, a plurality of (four here) ND filters ND0, ND2, N as shown in FIG.
ND filter unit 120 whose transmittance is changed by the combination of D3 (Actual Application No. 57-34645)
Each ND filter is driven by a motor 121 by a cam 122 driven by a motor 121 at a light amount ratio given by
10 is controlled in 11 steps by being inserted into and removed from the optical path as shown in FIG. 3, and ND0 and ND2 are inserted in the optical path in FIG. 9, and the light quantity ratio ND = 1 /
16 are given. AS is the brightness ratio of the aperture stop 77, and assuming that 80% of the pupil diameter is the standard value, the brightness ratio AS is
Of 0.8 ² = 0.64. As shown in FIG. 11, Bi is the light amount ratio when the optical path of Bi 100% is 1, and Ob is the light amount ratio referred to from the magnification and type of the objective lens as shown in FIG. Lens SPLAN
It is set to 1 based on 10x. LA is an objective lens
SPLAN 10 ×, light intensity ratio ND = 1, brightness ratio AS = 1, B
i is the image plane illuminance in the optical path of 100%, and LA = 189 lx is used as a constant in this embodiment.

In this state, the image plane illuminance L is always 0.5 to 1 l.
To keep it in the x range, From the formula by the target value Therefore, ND = 0.707 / (189 * 0.64 * Ob * Bi) = 5.84 * 10 < ^-3 > / (Ob * Bi) ... is obtained, and the target value of the light amount ratio of the ND filter is given.

By the way, the ND filter unit 120
Is composed of a combination of four ND filters, the target value of ND according to the formula must be given with a resolution of 2 ^1/4 . Therefore, taking the logarithm with the base of 2 ^1/4 in the equation, log aND = -30 -log a Ob -log aBi .... Therefore, in order to obtain the actual combination of ND filters, the table of FIG.
Find log a Ob, and log a Bi from the table in FIG.
Then, log a ND is obtained from the equation. Thus this lo
The light amount ratio ND is obtained based on the table shown in FIG. 13 corresponding to ga ND, and the ND filter control unit 80 controls the ND filter to give this light amount ratio ND according to FIG. 10 to 1
The table of No. 3 is stored in the ROM 54 as data to be read as needed.

Here, the objective lens SPLAN 10 ×,
In the case of the optical path of Bi 20%, from FIG. 11 and FIG.
ga Bi = -9, log a Ob = 0, log a ND = -30-0-(-9) = -21 is obtained from the equation, and ND = 1/32 from the table of Fig. 13, which is shown in Fig. 10. According to the table, if ND0 and ND3 are inserted in the optical path, proper brightness can be obtained. Therefore, C
The PU 51 outputs a signal to the ND filter switching drive unit 80 to insert the ND filters ND0 and ND3 into the optical path so that the brightness of the observation system can be optimally set to be constant.

In this way, a series of related operations at the time of setting the data of the objective lens are performed, but when performing the data setting of a plurality of objective lenses, the above operation is performed for each objective lens. Further, the data of the objective lens once set is stored in the RAM 52 as the objective data table 100 of FIG. 5 together with the revolver position, and the RAM 52 is backed up by the battery 53 even when the power is cut off. Good. Further, since the objective data table 100 is stored, for example, when the revolver 71 is switched, the revolver position is detected, the magnification and type of the objective lens are read out by the objective data table 100, and the CPU 51 calculates as described above. Alternatively, the optimum condenser lens 75 and field stop 7 are automatically referred by referring to the table data stored in the ROM.
9 and the aperture diameter of the aperture stop 77 and the combination of the ND filter unit 81 are determined, and a signal is output to each drive unit for automatic setting. Incidentally, not only when the objective lens is switched, but also when the observation system (Bi) optical path is switched, the photographing lens 67 is switched, etc., the above automatic setting is performed in exactly the same manner. It is possible to perform a speculum that is open and has no operational error.

After the data set and its related operation are performed as described above, the optical system background data for automatic focusing is input, and this is the stage 7.
No. 3, the illumination unevenness of the image projected on the image pickup device 61 and the unevenness of the optical system, and the image pickup device 61
This is done to correct the noise pattern that is permanently present in the autofocus. In addition, this correction data input sequence is the same as the objective data table 10 of the RAM 52.
ND to input as optimum projection image data by 0
Filter unit 81, field stop 79, aperture stop 77
Set the data of. Two pieces of projection image data A and B obtained by pupil division by the pupil division chopper 85 are obtained by the image pickup device 61 as shown in FIG. 14, and this data is used as correction data. Here, the x-axis shows the bits of the image sensor, and the y-axis shows the output signal of each bit of the image sensor, that is, the light amount. When the correction coefficient for each bit is obtained based on this data, the correction coefficients A'and B'for the correction data A and B are expressed as shown in FIG. 15, and the correction coefficients A'and B'are stored in the RAM.
The correction coefficient for each of the objective lenses connected to the revolver 71 is sequentially stored in the RAM 52 by inputting the data to the objective data table 52 for comparison with the objective data table 100, and a projected image from the image pickup device 61 at the time of automatic focusing. When the data is input, the correction coefficient calculation is performed on the projection image data to improve the accuracy of the projection image data.

After this correction data input sequence, ND
The filter 81, the field stop 79, and the aperture stop 77 are set to the above-mentioned values determined so as to show the best conditions for observation. The data set of the objective lens and the operation related thereto are performed as described above, and are summarized as shown in the flowchart of FIG.

Next, automatic focusing will be described. Figure 1
7 is a block diagram of a control circuit for automatic focusing, 130 is an amplifier, and 131 is a sample hold circuit. The image pickup signal for the image projected on the image pickup device 61 is amplified by the amplifier 130, and is sampled and held by the sample hold circuit 13.
The 512-bit pixel information signal is converted into a digital signal by the A / D converter 63 via 1 and is input to the CPU 51 and then stored in the RAM 52. At this time, as described above, after the correction coefficient calculation is performed by the calculator 55 using the correction coefficient stored in the RAM 52 in advance (corresponding to the objective lens detected by the objective lens switching drive unit 70), the image pickup signal is stored in the RAM 52. It will be remembered in. In addition, the CPU 51 drives the chopper for pupil division via the chopper drive unit 84, so that the CPU shown in FIG.
Since the pupil position of the optical system is divided and switched to A and B as shown in, the calculation for the focus is performed by the calculator 55 based on the image pickup signal from the image pickup device 61 for the pupil positions A and B. As a result, the movement amount of the stage 73 is obtained,
By inputting this to the CPU 51, the CPU 41
Drives the stage 73 to the in-focus position via the focusing stage drive unit 72.

Here, the optical principle of focusing by pupil division will be described. 18, 132 is an imaging lens, 133 is a light blocking plate having an opening 133a disposed in front of the imaging lens 132 near the pupil, 134 is an image plane, and the opening 133a of the light blocking plate 133 is shown in FIG. In the case of the position A as shown in (a), the image Q is formed on the image plane 3 when the image is focused, and when the image is out of focus, the image Q is defocused in the position perpendicular to the optical axis O with respect to the image Q. When the images Q ₁ and Q ₂ are formed and the opening 133a of the light shielding plate 133 is located at the position B as shown in FIG. 18B, the image Q'is formed on the image plane 3 at the time of focusing, and the unfocused image is formed. When the lens is in focus, similarly blurred images Q ₁ ′ and Q ₂ ′
Is formed.

Thus, when the opening 133a of the light shielding plate 133 is moved from the position A to the position B or vice versa, the images Q and Q'in focus are exactly the same, but the image in non-focus is Q _1. To Q ₁ ′ or vice versa or Q ₂ to Q ₂ ′
Move to or vice versa. Therefore, by arranging the image sensor on the image surface 134 and detecting the moving state of the image, whether the image is in focus, whether it is the front focus or the rear focus when out of focus, and the focus shift in that case. You can know the quantity. Based on this principle, the imaging signals for the two pupil positions divided by the pupil division chopper are f _A ,
indicated by f _B, this f _A, the correlation operation expression from f _B Thus, the correlation calculation is performed by shifting f _B with respect to f _A by δ, and δ ′ (see FIG. 19B) that gives the minimum value of R (δ) is the phase difference in this case. However, ABS {α} indicates the absolute value of α. The area of the shaded area in FIG. 19 is represented by R (0) where δ = 0 in the equation. Thus, automatic focusing is performed by controlling this δ'to zero.

FIG. 20 shows an embodiment of a pupil division chopper, and 135 is a chopper, which is rotatably arranged around a rotation axis 136, and a pupil 137 at a position (a).
Only the light flux passing through the lower half of the pupil reaches the image sensor through the opening 135a, and at the position (b), only the light flux passing through the upper half of the pupil 137 passes through the outside of the chopper 135 and reaches the image sensor. The division can be performed, and when the pupil division is not performed, the whole is retracted to the outside of the pupil 137 as in (c). Further, when obtaining the contrast value described later, the chopper 135 may be set to the position of FIG. 20A or 20B, but in this embodiment, it is set to the position of FIG. There is. Further, the image sensor is, for example, 5
Comprised of a photodiode array consisting of 12 photodiodes operating in charge storage mode,
The output signal is proportional to the incident light amount (ft-Dd) × repetitive scanning time (second) and is as shown in FIG. Since this output signal has a saturation point, the CPU 51 switches the dimming circuit 82 for the light source 83 and the ND filter unit based on the objective data table 100 so that an appropriate amount of light is given to the image sensor. The optimum charge storage time can be set by controlling the unit 80 and giving information to the image pickup device drive circuit 61 about an appropriate repetitive scanning time.

The background data input, which has been briefly described for the automatic control of the illumination optical system, will be described in more detail with reference to the flowchart of FIG. When the data of the objective lens is input through the operation panel 64, the condenser lens 75, the aperture stop 77, the field stop 79, and the ND filter 81 corresponding to the objective lens are optimally switched and controlled, and at the same time, the background data input sequence is performed. Is started. First, the stage 73 is driven by the focusing stage drive unit 72 to a reference position set below the theoretical focus position. This reference position is set as follows. In FIG. 23, 14
0 is the objective lens, 141 is the upper limit position of the stage 73, and 1
42 is a lower limit position of the stage 73, 143 is a theoretical focus position, and 144 is a reference position, which is below the focus position 143 by the maximum thickness of the slide glasses 73a and the cover glasses 73b. Positions 141, 145, 146, 147
A position sensor such as a photo sensor for detecting 142 and 144.

Therefore, if the drive unit 72 is stopped when the position sensor 147 detects the position, the stage 73 is stopped at the reference position 144, and due to the variation in the thickness of the cover glass 73b and the slide glass 73a, the actual stage is stopped. The position of the stage 73 that gives the focus position of is always above the reference position 144. Further, when the stage 73 is brought to the upper limit position 141 or the lower limit position 142, the sensors 145 and 146 detect it and stop the drive unit 72, and at the time of automatic focusing, preferably at the same time unfocused. A display can be made. Thus, at the same time that the stage 73 is driven to the reference position, the beam splitter 16 (see FIGS. 1 and 2) is switched and driven, and the optical path to the image pickup device 19 is formed.

Further, based on the objective lens data, the aperture stop 7
7 and the field stop 79 are driven to the optimum stop diameters by the respective control drive units 76 and 78, and a dimmer 82 for the light source 83 and a switching drive unit 80 for the ND filter unit 81 are attached to the image sensor 61. On the other hand, it is controlled so as to obtain an optimum amount of light. At the same time, the drive unit 66 thereof is controlled so as to make the photographing lens 67 5 times larger. The taking lens 6
7 is made 5 times in order to match the resolution of the projected image formed on the image sensor 61 with the resolution of the image sensor itself, and the resolution Δx of the taking lens is Δx = ΔZ × NA = 0. 5λ / NA (where ΔZ = λ / (2NA ² ) (depth of focus)), and in the case of a 5 × magnification system, if the NA behind the objective lens is generally 0.04, then On the image side of the double magnification system, NA = 0.008, and if λ≈0.5, then Δx
= 31.25 (μm). Since the pitch between the sensors of the image sensor used here is 28 μm,
Sufficient imaging data resolution can be obtained for the projection image by the 5 × magnification system.

After the taking lens 67 is thus switched to 5 ×, an appropriate image pickup device charge accumulation time is calculated from the objective lens data to effectively use the dynamic range of the image pickup device 61, and the driving and image pickup signal processing circuit 62 is calculated. Sent as control data. Each drive unit 66, 68,
After the CPU 51 confirms that the 74, 76, 78, 80, and 82 have respectively actuated to the designated states, the chopper driving section 84 causes the pupil division chopper 85 to move the pupil division chopper 85 to the first pupil division position (for example, FIG. 20A). Position A), and the image pickup device data from the image pickup device 61 at this time is the CPU 5
1 and arithmetic processing is performed by the arithmetic unit 55, and stored in the RAM 52 as a correction coefficient of each bit. Next, the chopper 85 is driven to the second pupil division position (for example, the position shown in FIG. 20B) B, and the correction coefficient at this time is similarly stored in the RAM.
Stored in 52. This can be done for each objective when the objectives are switched.

Thus, after the correction coefficient is input to the RAM 52, the taking lens 67, the light source 83, the ND filter unit 81, the aperture stop 77, the field stop 79 and the beam splitter 16 are returned to the initial position or the setting state, and the chopper. Reference numeral 85 indicates a spot outside the optical path (position in FIG. 20C).

By executing the background data input sequence as described above, the image pickup data of the sample image obtained during the subsequent automatic focusing is calculated by the correction coefficient stored as the background data. As a result, higher precision automatic focusing becomes possible.

Next, the operation of automatic focusing will be described with reference to FIGS.
Objective lens SPLAN 1 according to the flowchart of FIG.
The case of 0x will be described. First, the conditions of the optical system for automatic focusing are set. When the switch 99 on the operation panel 86 is pressed, the CPU 51 causes the RAM 5 to change the switching state of each beam splitter regardless of the optical path.
2, and the beam splitter 16 (see FIG. 1) is driven by the optical path switching drive unit to form an optical path to the image sensor 61. At that time, the aperture values of the aperture diaphragm 77 and the field diaphragm 79, the switching state of the ND filter unit 81, and the dimming state of the light source 83 are respectively RAN.
52, the aperture stop 77, the field stop 79, and N are stored as in the case of inputting the background data.
The D filter unit 81 and the light source 83 are set so that the projected image on the image sensor 61 is optimum.

That is, according to the objective lens inserted in the optical path based on the objective data table 100, the aperture diameter of the aperture stop 77 is obtained when K2 = 1 in the formula (100% of the pupil diameter). The diaphragm diameter and the diaphragm diameter of the field diaphragm 79 are obtained when K1 = 1 in the formula (circumscribing the field of view), the ND filter unit 81 and the light source 83.
Is the image plane illuminance obtained from the formula Each of the CPU5 has a value such that the coefficient 0.707 of 1 is set to 1.
1 and the calculator 55, and is set by each drive unit and the dimming circuit. Further, in order to increase the resolution of the projected image on the image pickup device 61, the taking lens 67 is set to 5 ×.

After the above settings are made, the CPU 5
1 confirms that the pupil division chopper 85 is moved to the first pupil decomposition position (FIG. 20 (a)) A by the chopper driving unit 84, and at the same time, the position of the stage 73 is detected. When the stage 73 is above the reference position 144, the image pickup data at the pupil decomposition position A is input from the image pickup device 61 to the CPU 51, and the CPU 51 calculates the image pickup data as background data by the correction coefficient stored in the RAM 52. Process and get f _A , which is R
The contrast value is calculated while being stored in the AM 52. Here, the calculation of the contrast value is performed as follows with reference to FIG. 26, for example. The 512-bit sensor on the image sensor 61 is divided into five groups of a, b, c, d, and e, and f (x)
If x is the signal of the x-th bit and x is calculated every four, the contrast C becomes It is represented by. This means that the absolute value of the difference between the signals of the sensors, which are separated by 5 bits, is calculated every 4 bits.

Therefore, the contrast Ca of the group a is Becomes Similarly, the contrast of each group is calculated to calculate the overall contrast value.

When the contrast value calculated in this way is equal to or less than the preset threshold value, and when the stage 73 is below the reference position 144, the stage drive unit 72 moves the stage 73 to the reference position. 144
The image pickup data at the pupil position A is again calculated and stored in the RAM 52, and the contrast value is calculated. If the contrast value is equal to or less than the threshold value, the stage 73 is moved upward by 100 μm, and after confirming that the position of the stage 73 at this time is not the upper limit position 141, the imaging data at the pupil position A is calculated again. The processed value is processed and stored in the RAM 52, and the contrast value is calculated. This operation is repeated until the contrast value becomes equal to or higher than the threshold value. When the stage 73 reaches the upper limit position 141 in the middle, this is detected by the position sensor 145. By doing so, the above operation is interrupted, and a non-focus indication is displayed on the operation panel 64.

When the contrast value exceeds the threshold value,
The pupil division chopper 85 is moved to the second position by the chopper drive unit 84.
The pupil division position (Fig. 20 (b)) B of
The image pickup data at the division position B from the image pickup device 61 is CP.
U51 is input to the CPU 51, and the CPU 51 outputs this imaging data
Stored in RAM 52 as background data input
F is calculated by the correction coefficient_BGet RA first
F stored in M52 _AIs read out by the calculator 55
Perform the correlation operation shown in the formula to give the minimum value of R (δ)
Δ ′ (phase difference), and based on this phase difference δ ′,
The amount of movement of the stage 73 is determined, and the stage drive unit 72 determines
The stage 73 is moved. Then again for pupil division
By driving the hopper 85, the imaging data at the pupil positions A and B are
Data f_A, F_BAnd R (δ) by the correlation calculation
Δ ′ which gives the minimum value of
The operation of calculation is repeated. When δ ′ becomes 0, the sum
When the focus is confirmed, the above operation is interrupted, and the operation panel 64
The focus is displayed.

Thus, after the in-focus or out-of-focus surface is made on the operation panel 64, each optical system element is automatically focused based on the data stored in the RAM 52 at the beginning of the automatic focusing operation. You can return to the previous state.
That is, the pupil division chopper 85 is located outside the optical path (FIG. 20 (c)).
The photographing lens 67 is switched to the original magnification, and the aperture stop 77, the field stop 79, the ND filter unit and the light source 83 are returned to the original control and switching states. Further, the beam splitter 16 is inserted into the optical path to form the optical path of the photography system. This completes the automatic focusing operation.

As described above, according to the present embodiment, 1) the focusing operation is automated, which facilitates the operation by the microscope operator, prevents operation errors, shortens the required time, and enables focusing. Accuracy is improved. 2) Since the correction coefficient of the imaged data is stored in the RAM as the background data, the focusing accuracy is improved, and the operability is improved by easily inputting the correction coefficient. 3) At the time of automatic focusing, each optical system element is automatically set to a suitable state, and after the completion of automatic focusing, each optical system element is automatically returned to its previous state. 4) When automatic focusing is performed, optical conditions such as a diaphragm and brightness are calculated to be optimum values based on the objective lens data and automatically set, so that accuracy of imaging data is improved. 5) For automatic focusing, by providing the stage reference position near the theoretical focus position of the objective lens,
Focusing time is greatly shortened, which is particularly effective for focusing with a high-magnification objective lens, and the automatic focusing operation is performed while monitoring the stage position. Focusing accuracy is improved because automatic focusing is performed. 6) Since the correlation calculation formula and the contrast value are used together as the calculation process for focusing, the processing time is shortened and the focusing accuracy is improved. The effect is obtained, which is extremely convenient.

[0044]

As described above, in the microscope equipped with the automatic focusing device according to the present invention, the reference position of the stage is provided during focusing, so that the focusing time can be greatly shortened. In particular, it has a practically important advantage that it is effective in the case of focusing in a high-magnification objective lens.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an optical system of a microscope.

2 is a block diagram of a control system according to the invention for the microscope of FIG.

FIG. 3 is a detailed block diagram showing a control device of an embodiment of a microscope according to the present invention.

4 is a front view showing an example of an operation panel in the control device of FIG.

FIG. 5 is a chart showing an objective data table.

FIG. 6 is a chart showing a contrast between an objective lens and a condenser lens.

FIG. 7 is a chart showing FNo. (Field number) of an optical path.

FIG. 8 is a block diagram of aperture control.

FIG. 9 is a diagram showing an example of an ND filter unit.

FIG. 10 is a chart showing a light amount ratio depending on a combination of ND filters.

FIG. 11 is a chart showing a light amount ratio Bi according to an optical path.

FIG. 12 is a chart showing a light amount ratio Ob by an objective lens.

FIG. 13 is a chart showing a light amount ratio ND by an ND filter.

FIG. 14 is a graph showing correction data of a projected image on an image sensor.

FIG. 15 is a graph showing a correction coefficient of a projected image on an image sensor.

FIG. 16 is a flow chart of control when setting objective lens data.

FIG. 17 is a block diagram of a control circuit for automatic focusing.

FIG. 18 is a schematic diagram showing the principle of focusing by pupil division.

FIG. 19 is a graph showing imaging data by pupil division and a phase difference by its correlation calculation.

FIG. 20 is a diagram showing an example of a pupil division chopper in each operating state.

FIG. 21 is a graph showing the output of the image sensor.

FIG. 22 is a flowchart of background data input for automatic focusing.

FIG. 23 is a diagram showing a reference position of a stage.

FIG. 24 is part of a flow chart for automatic focusing.

FIG. 25 is a portion of an autofocusing flow chart connected to the flow chart of FIG. 24.

FIG. 26 is a diagram showing each group when a contrast is obtained.

[Explanation of symbols]

7 ...- Stage, 8 ...- Objective lens, 9 ... Revolver, 19-Imaging element, 21-Imaging signal processing circuit, 2
6 ... Objective lens switching drive unit, 27 ... Focusing drive unit, 3
2 ... CPU, 35 ... Storage unit, 61 ... Image sensor, 6
2 ... Drive and imaging signal processing circuit, 70 ... Objective lens switching drive unit, 71 ... Revolver, 72 ... Focusing stage drive unit, 73 ... Stage, 135. ... pupil division chopper, 100 ... objective data table, 140 ... objective lens, 141 ... upper limit position, 142 ... lower limit position, 1
43 ... Focus position, 144 ... Reference position, 145, 1
46,147 ... Position sensor.

Claims (1)

[Claims] 1. A microscope equipped with an automatic focusing device, wherein a stage is moved up and down by a focusing drive unit based on the amount of light received by an image pickup device to stop the stage at a focus position, with respect to an objective lens. Means for setting a position slightly deviated from the theoretical focus position in the optical path direction as a reference position, reference position moving means for moving the stage to the reference position during focus adjustment, and the reference position at predetermined intervals from the reference position. A microscope equipped with an automatic focusing device, comprising: a means for moving the stage in a theoretical focusing position direction; and a stage stopping means for stopping the stage at the focusing position.