JP2009116271A - Focusing arrangement and microscope apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focusing arrangement enabling preferable focusing, and a microscope apparatus having it. <P>SOLUTION: The arrangement includes: a first detecting means for producing a first defocusing signal showing displacement of the focal position of an objective lens and an imaging position of a transmission object; a determination means for determining whether focusing is executed for a desired surface out of a plurality of reflection surfaces based on an output signal of the focus sensing light receiving element and the reference position by preliminarily storing a reference position on a focus sensing light receiving element for equally dividing the light receiving amount of the pattern image at the time of being focused in the lateral displacement direction of a pattern image for at least one reflection surface out of a plurality of reflection surfaces, and an adjusting means for monitoring a first evaluation value showing goodness/badness of the first defocusing signal and adjusting the interval between the objective lens and the transmission object based on the first defocusing signal in the case where the determination means determines that the evaluation value exceeds a first threshold value and that the focusing operation is carried out to the desired surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a focus adjustment apparatus applied to a microscope apparatus and the like, and a microscope apparatus including the same.

Lens focus detection methods include a slit projection method mainly mounted on an industrial microscope and a contrast detection method mainly mounted on a biological microscope. An optical system that can switch the focus detection method between two types has already been proposed (see Patent Document 1).
JP 2002-277729 A

By the way, in a transmissive object having a plurality of reflecting surfaces (for example, a front surface and a back surface) such as glass, reflected light is generated by the plurality of reflecting surfaces. Therefore, there is a case where the surface to be focused cannot be focused. In addition, an object such as glass that is the subject of focus adjustment to change the observation location
When moved in the Y direction, the focus position may easily shift due to deflection, thickness unevenness, stage flatness, and the like, and a surface that is not a desired surface may be focused.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a focus adjustment apparatus and a microscope apparatus that can perform suitable focus adjustment on a transmissive object having a plurality of reflecting surfaces.

  The focus adjustment apparatus of the present invention is a focus adjustment apparatus that performs focus adjustment on a transmission object having a plurality of reflection surfaces, and a pattern projection unit that projects a pattern onto the transmission object via a part of the pupil of an objective lens. A lateral deviation amount of the pattern image is obtained on the basis of a first light receiving means having a plurality of linear focus detection light receiving elements for receiving the pattern image reflected from the transmission object, and an output of the first light receiving means. First detection means for generating a first defocus signal indicating a deviation in the optical axis direction between the focal position of the objective lens and the imaging position of the transmission object based on the lateral deviation amount; and the plurality of reflection surfaces The reference position on the focus detection light-receiving element that equally divides the received light amount of the pattern image at the time of focusing in the lateral shift direction of the pattern image with respect to at least one of the reflection surfaces is previously recorded. And determining means for determining whether or not focus adjustment is performed on a desired surface among the plurality of reflection surfaces based on an output signal of the light receiving element for focus detection and the reference position; When a first evaluation value indicating whether the first defocus signal is good or not is monitored, the evaluation value exceeds a first threshold value, and focus adjustment is performed on the desired surface by the determination unit. When the determination is made, adjustment means is provided for adjusting the distance between the objective lens and the transmission object based on the first defocus signal.

  The microscope apparatus of the present invention includes a microscope optical system for observing an image captured by an objective lens, and the above-described focus adjustment apparatus that performs focus adjustment of the objective lens.

  ADVANTAGE OF THE INVENTION According to this invention, the focus adjustment apparatus and microscope apparatus which can perform suitable focus adjustment in the transmissive object which has several reflective surfaces can be provided.

  Hereinafter, embodiments of the focus adjustment device of the present invention will be described.

  FIG. 1 is a configuration diagram of the focus adjustment apparatus of the present embodiment. The focus adjustment apparatus shown in FIG. 1 is a hybrid type focus adjustment apparatus in which both a slit projection type focus detection optical system and a contrast detection type focus detection optical system are mounted.

  First, a slit projection type focus detection optical system will be described. In FIG. 1, an LED 7 emits infrared light for slit projection. Hereinafter, this infrared light is referred to as “slit projection AF light”. The slit projection AF light emitted from the LED 7 includes a slit plate 8, a collector lens 9, a pupil mask 10, a half mirror 11, a half mirror 16, a dichroic mirror 4, a first objective lens 3, a sample 2, and a first objective lens. 3, the dichroic mirror 4, the half mirror 16, the second objective lens 17, and the three-divided prism 18, followed by branching into three lights La, Lb, and Lc, and different regions 22 a, 22 b, and 22 c of the line sensor 22. Incident individually.

  Of these, the three-divided prism 18 branches incident slit projection AF light into two lights at the first semi-transmissive surface 19, and splits one light into two lights at the second semi-transmissive surface 20. And the one light after the branching is reflected on the reflecting surface 21. Therefore, an optical path difference is given between the three lights La, Lb, and Lc before entering the line sensor 22. Among these, the optical path difference between the light La and the light Lb and the optical path difference between the light Lb and the light Lc are equal to each other.

  Here, one line sensor 22 is shared for detecting the light La, Lb, and Lc, but three line sensors that individually detect the light La, Lb, and Lc may be used. An image sensor may be used instead of the line sensor.

  Here, a slit opening is formed in the center of the slit plate 8 as shown in FIG. Therefore, the slit projection AF light forms a slit-like infrared image in the vicinity of the object plane (here, the sample plane 2a). At this time, the slit projection type AF light reflected by the sample surface 2 a forms a slit-like infrared image in each of the regions 22 a, 22 b, and 22 c of the line sensor 22. Hereinafter, this infrared image is referred to as a “slit image”. The slit width direction of the slit image and the line direction of the line sensor 22 intersect each other.

  The pupil mask 10 transmits one of two lights obtained by dividing the slit projection AF light on a plane including the optical axis and shields the other. Therefore, when the slit projection type AF light reciprocates through the first objective lens 3, it passes through different positions on the pupil of the first objective lens 3 in the forward path and the backward path. Therefore, the slit image formed in each of the regions 22a, 22b, and 22c corresponds to the defocus amount of the first objective lens 3 (the shift in the optical axis direction between the focal position of the first objective lens 3 and the sample surface 2a). Slip sideways. Therefore, a defocus signal of the slit projection method can be generated from the lateral shift amount of the slit image formed in any one of the regions (preferably the region 22a). It is assumed that the center of gravity position of the slit image formed in the region 22a when the defocus amount of the first objective lens 3 is zero is measured in advance.

  Next, a contrast detection type focus detection optical system will be described. In FIG. 1, an LED 14 emits infrared light for a contrast detection method. Hereinafter, this infrared light is referred to as “contrast detection AF light”. The contrast detection AF light emitted from the LED 14 includes a slit plate 13, a collector lens 12, a half mirror 11, a half mirror 16, a dichroic mirror 4, a first objective lens 3, a sample 2, a first objective lens 3, and a dichroic mirror. 4. After passing through the half mirror 16, the second objective lens 17, and the three-divided prism 18 in order, it is branched into three lights La, Lb, and Lc, and individually into different regions 22 a, 22 b, and 22 c of the line sensor 22. Incident. That is, the contrast detection type focus detection optical system shares the half mirror 16, the second objective lens 17, the three-divided prism 18, and the line sensor 22 with the slit projection type focus detection optical system.

  Here, 18 slit openings are formed in the center of the slit plate 13 as shown in FIG. Therefore, the contrast detection AF light forms a striped infrared image in the vicinity of the sample surface 2a. At this time, the contrast detection AF light reflected by the sample surface 2 a forms a stripe-shaped infrared image in each of the regions 22 a, 22 b, and 22 c of the line sensor 22. Hereinafter, this infrared image is referred to as a “striped image”. The stripe image pitch direction and the line sensor 22 line direction intersect each other.

  However, since an optical path difference is given between the light La, Lb, and Lc, the formation position of the stripe image by the light La, the stripe image by the light Lb, and the stripe image by the light Lc is shifted in the optical axis direction. . For example, as shown in FIG. 1, when the stripe image by the light Lb exists on the line sensor 22, the stripe image by the light La is formed on the back side of the line sensor 22, and the stripe image by the light Lc is on the front side of the line sensor 22. It is formed. Therefore, the degree of blur (that is, contrast) differs between the stripe image formed in the region 22a of the line sensor 22, the stripe image formed in the region 22b, and the stripe image formed in the region 22c.

  Further, the contrast relationship of the stripe images changes according to the defocus amount of the first objective lens 3. Therefore, the contrast detection method defocus signal is obtained from the contrast relationship of the stripe images formed in the regions 22a, 22b, and 22c (preferably, the contrast relationship of the stripe images formed in the regions 22a and 22c). Can be generated.

  Note that the number of slit openings formed in the slit plate 13, that is, the number of stripes of the stripe image can be changed according to the pattern of the specimen 2. The combination of the reflectance of the semi-transmissive surface 19 of the three-divided prism 18, the reflectance of the semi-transmissive surface 20, and the reflectance of the reflective surface 21 is optimal in advance so that the light amounts of the three lights La, Lb, and Lc are substantially equal. It has become. Further, the positional relationship between the second objective lens 17 and the line sensor 22 is adjusted in advance so that a stripe image by the light Lb is formed on the line sensor 22 when the defocus amount of the first objective lens 3 is zero. Has been.

  In the above focus adjustment apparatus, the CPU 24 can perform switching control between the LED 7 that is a slit projection type light source and the LED 14 that is a contrast detection type light source via the LED switching unit 26. Since the slit projection type slit image is formed during the period in which the LED 7 is lit, it is possible to generate a slit projection type defocus signal from the output signal of the line sensor 22. On the other hand, since the contrast detection type stripe image is formed during the period when the LED 14 is lit, it is possible to generate a contrast detection type defocus signal from the output signal of the line sensor 22. Hereinafter, the state in which the slit projection type light source is lit is referred to as “slit projection mode”, and the state in which the contrast detection type light source is lit is referred to as “contrast detection mode”.

  The output signal of the line sensor 22 is taken into the signal processing unit 23. When the signal processing unit 23 generates some signals based on the captured signals, the signal processing unit 23 gives them to the CPU 24. When the CPU 24 generates a slit projection type or contrast detection type defocus signal based on the given signal, the CPU 24 designates a drive direction and a drive speed in accordance with the defocus signal to the vertical movement drive unit (pulse motor or the like) 25. . The vertical movement drive unit 25 adjusts the focus of the first objective lens 3 by driving the first objective lens 3 in the optical axis direction at a designated drive direction and drive speed. Although the vertical movement drive unit 25 may be driven by the stage 1 instead of the first objective lens 3, the following description is based on the assumption that the first objective lens 3 is used.

  The CPU 24 can also control the light amount of the LED 7 and the light amount of the LED 14 via the LED switching unit 26, and can also switch the charge accumulation time (scanning time) of the line sensor 22 as necessary.

  Next, signal generation operations of the signal processing unit 23 and the CPU 24 in the slit projection mode will be described.

  2, 3 and 4 are diagrams for explaining the signal generation operation in the slit projection mode. 2, 3 and 4 show the relationship between the defocus amount of the first objective lens 3 and the sensor signal in the region 22b. (A) shows the defocus amount, (b) shows the behavior of the light La, Lb, and Lc, (c) shows the sensor signal of the region 22b, and (d) shows the integrated value of the sensor signal.

The signal processing unit 23 includes a peak voltage signal V ₁₀₂ which is obtained by peak-holding the sensor signals in the region 22b, the integrated signal V _F which is obtained by integrating the sensor signal region 22b from one end (F side) to the center of gravity position 100 Then, an integrated signal V _R obtained by integrating the sensor signal of the region 22b from the center of gravity position 100 to the other end (R side) is acquired and given to the CPU 24.

The CPU 24 generates a difference signal (V _F −V _R ) between the integration signal V _F and the integration signal V _R given from the signal processing unit 23 as a defocus signal of the slit projection method. The peak voltage signal V ₁₀₂ supplied from the signal processing unit 23 is used as an evaluation value for evaluating the generation state of defocus signals slit projecting system.

As shown in FIG. 2A, when the focal position of the first objective lens 3 is on the back side (rear pin position) from the sample surface 2a, the sensor signal in the region 22b is as shown in FIG. It is distributed on the R side from the center of gravity position 100. At this time, as shown in FIG. 2D, since the magnitude relationship between the integration signal V _F and the integration signal V _R is V _F <V _R , the defocus signal (V _F −V _R ) is negative.

As shown in FIG. 3A, when the focal position of the first objective lens 3 is at the sample surface 2a (in-focus position), the sensor signal in the region 22b is the center of gravity position 100 as shown in FIG. Distributed. At this time, as shown in FIG. _3D , the magnitude relationship between the integration signal V _F and the integration signal V _R is V _F = V _R , so the defocus signal (V _F −V _R ) is zero.

As shown in FIG. 4A, when the focal position of the first objective lens 3 is in front of the sample surface 2a (front pin position), the sensor signal in the region 22b is as shown in FIG. 4C. It is distributed on the F side from the center of gravity position 100. At this time, as shown in FIG. 4D, since the magnitude relationship between the integration signal V _F and the integration signal V _R is V _F > V _R , the defocus signal (V _F −V _R ) is positive.

Reference numeral 41 in FIG. 5 indicates the relationship between the defocus amount of the first objective lens 3 and the slit projection type defocus signal (V _F −V _R ). As shown in FIG. 5, when the first objective lens 3 is in the front pin state, the defocus signal (V _F −V _R ) becomes positive, and the defocus signal (V _F −V _R ) becomes zero as the focus state is approached. Get closer to. When the first objective lens 3 is in the rear pin state, the defocus signal (V _F −V _R ) becomes negative, and the defocus signal (V _F −V _R ) approaches zero as the focus state is approached.

Thus, upward (specimen driving direction of the first objective lens 3 when the case of performing the focus adjustment by the defocus signal (V _F -V _R), the polarity of the defocus signal (V _F -V _R) is negative 2), when the polarity of the defocus signal (V _F −V _R ) is positive, the driving direction of the first objective lens 3 may be the downward direction (the direction approaching the sample 2).

  Next, signal generation operations of the signal processing unit 23 and the CPU 24 in the contrast detection mode will be described.

  6, 7 and 8 are diagrams for explaining the signal generation operation in the contrast detection mode. 6, 7 and 8 show the relationship between the defocus amount of the first objective lens 3 and the sensor signals of the regions 22a, 22b and 22c. (A) is the defocus amount, (b) is the behavior of the light La, Lb, and Lc, (c) is the contrast signal of the regions 22a, 22b, and 22c, and (d) is the integral value of these contrast signals. .

The signal processing unit 23 removes a DC component from the sensor signal of each region, and acquires a contrast signal of each region. Then, the peak voltage signal V ₁₁₀ which is obtained a contrast signal of the entire area and a peak hold, the integral signal V _a of the contrast signal region 22a, and the integrated signal V _b of the contrast signal region 22b, contrast signal region 22c It acquires the integrated signal V _c gives it to the CPU 24.

The CPU 24 generates _a difference signal (V _a −V _c ) between the integration signal V _a and the integration signal V _c given from the signal processing unit 23 and further normalizes the difference signal (V _a −V _c ) ( V _a −V _c ) / (V _a + V _c ) is generated as a defocus signal of the contrast detection method. Note that the peak voltage signal V ₁₁₀ and the integration signals V _a and V _c given from the signal processing unit 23 are used as evaluation values for evaluating the generation state of the contrast detection type defocus signal.

As shown in FIG. 6A, when the focal position of the first objective lens 3 is on the back side (rear pin position) from the sample surface 2a, the contrast signal in the region 22c is displayed as shown in FIG. 6C. A peak appears. At this time, as shown in FIG. 6D, the magnitude relationship between the integrated signals V _a and V _c is V _a <V _c , so that the defocus signal (V _a −V _c ) / (V _a + V _c). ) Is negative.

As shown in FIG. 7B, when the focal position of the first objective lens 3 is at the sample surface 2a (in-focus position), a peak appears in the contrast signal of the region 22b as shown in FIG. 7C. To do. At this time, as shown in FIG. 7D, the magnitude relationship between the integration signals V _a and V _c is V _a = V _c , so that the defocus signal (V _a −V _c ) / (V _a + V _c). ) Is zero.

As shown in FIG. 8A, when the focal position of the first objective lens 3 is on the front side (front pin position) with respect to the sample surface 2a, a peak appears in the contrast signal of the region 22a as shown in FIG. 8C. A signal appears. At this time, as shown in FIG. 8D, the magnitude relationship between the integrated signals V _a and V _c is V _a > V _c , so that the defocus signal (V _a −V _c ) / (V _a + V _c). ) Is positive.

Reference numeral 42 in FIG. 5 indicates the relationship between the defocus amount of the first objective lens 3 and the defocus signal (V _a −V _c ) / (V _a + V _c ) of the contrast detection method. As shown in FIG. 5, when the first objective lens 3 is in the front pin state, the defocus signal (V _a −V _c ) / (V _a + V _c ) becomes positive, and the defocus signal (V _a −V _c ) / (V _a + V _c ) approaches zero. When the first objective lens 3 is in the rear-pin state, the defocus signal (V _a −V _c ) / (V _a + V _c ) is negative, and the defocus signal (V _a −V _c ) / (V _a + V _c ) approaches zero.

Therefore, when adjusting the focus by the defocus signal _{(V a -V c) / (} V a + V c) , the polarity of the defocus signal _{(V a -V c) / (} V a + V c) is negative Sometimes, the driving direction of the first objective lens 3 is the upward direction (the direction away from the sample 2), and when the defocus signal (V _a −V _c ) / (V _a + V _c ) is positive, the first objective lens 3 is positive. The driving direction may be a downward direction (a direction approaching the sample 2).

  The focus adjustment apparatus having the above-described configuration includes the first focus adjustment mode for performing normal focus adjustment, and the second focus for performing focus adjustment on a transmissive object having a plurality of reflecting surfaces (for example, front and back surfaces) such as glass. And an adjustment mode. The first focus adjustment mode and the second focus adjustment mode are selected by the user via an operation unit (not shown). In addition, it is good also as a structure which selects either 1st focus adjustment mode and 2nd focus adjustment mode automatically according to the reflected light etc. from the object which is the object of focus adjustment. Or it is good also as a structure provided with operation members, such as a switch which provides only a 2nd focus adjustment mode and designates a desired reflective surface.

  First, the operation of the CPU 24 when the first focus adjustment mode is executed will be described. FIG. 9 is a flowchart showing the operation of the CPU 24 when the first focus adjustment mode is executed.

  Step S1: At the start of the flow, the distance between the first objective lens 3 and the sample 2 is secured to some extent.

  Step S2: The CPU 24 turns on the LED 14 which is a contrast detection type light source and turns off the LED 7 which is a slit projection type light source. Further, the CPU 24 operates the signal processing unit 23 in the contrast detection mode.

Step S3: CPU 24, the charge accumulation time (scan time) standard values of the line sensor 22 (e.g., 2.7 ms) is set to, refer to peak voltage signal V ₁₁₀ supplied from the signal processing unit 23 at this time. The CPU24 adjusts the amount of light LED14 order to the peak voltage signal V ₁₁₀ to or higher than the threshold V _201.

Step S4: CPU 24 refers to the peak voltage signal V ₁₁₀ supplied from the signal processing unit 23 after adjusting, if the peak voltage signal V ₁₁₀ has been a threshold V ₂₀₁ or proceeds to step S5, less than the threshold V ₂₀₁ If it is, it is determined that the defocus signal of the contrast detection method cannot be generated satisfactorily (focus detection by the contrast detection method is impossible), and the process proceeds to step S11.

Step S5: CPU 24, in order to integrate the signal supplied from the signal processing unit 23 V _a, the value of V _c equal to or higher than the threshold V _202, adjusts the gain thereof integral signal V _a, V _c.

Step S6: CPU 24, the gain-adjusted in the integrated signal V _a, compared with the V _c and the threshold V _202, the integrated signal V _a, defocus contrast detection method as long as at least one of the threshold value V ₂₀₂ or more V _c it is determined that signal can be generated satisfactorily (can focus detection by the contrast detection method), the process proceeds to step S7, the integrated signal V _a, the focus detection by the contrast detection method if both V _c is less than the threshold value V ₂₀₂ not It judges that it is possible and progresses to step S11.

Step S7: The CPU 24 generates a contrast detection type defocus signal (V _a −V _c ) / (V _a + V _c ) based on the integrated signals V _a and V _c after gain adjustment.

Step S8: The CPU 24 refers to the absolute value of the generated defocus signal (V _a −V _c ) / (V _a + V _c ) and compares it with the threshold value V ₇₀ . If there were less than the threshold value V _70, it is determined that contains the sample surface 2a in a first focus depth of the objective lens 3 proceeds to step S9, when was the threshold V ₇₀ above, the first objective lens It is determined that the sample surface 2a is not within the focal depth of 3, and the process proceeds to step S10.

  Step S9: The CPU 24 sets the driving speed of the first objective lens 3 to zero and ends the flow.

Step S10: CPU 24 refers to the polarity of the defocus signal _{(V a -V c) / (} V a + V c) , the polarity of the defocus signal _{(V a -V c) / (} V a + V c) is negative If the driving direction of the first objective lens 3 is set to the upward direction and the polarity of the defocus signal (V _a −V _c ) / (V _a + V _c ) is positive, The driving direction of the objective lens 3 is set downward. When the absolute value of the defocus signal (V _a −V _c ) / (V _a + V _c ) is less than the threshold value V ₇₁ , the absolute value of the driving speed of the first objective lens 3 is set to a small value V ₇₄ . and, if there was a threshold V ₇₁ or set to the value V ₇₃ of moderate absolute value of the drive speed of the first objective lens 3, the flow returns to step S3. The values V ₇₄ and V ₇₃ satisfy the relationship V ₇₄ <V ₇₃ .

  Step S11: The CPU 24 turns on the LED 7 which is a slit projection type light source and turns off the LED 14 which is a contrast detection type light source. Further, the CPU 24 operates the signal processing unit 23 in the slit projection mode.

Step S12: the charge accumulation time of the line sensor 22 (scan time) standard value (e.g., 2.7 ms) is set to, refer to peak voltage signal V ₁₀₂ supplied from the signal processing unit 23 at this time. Further CPU24 adjusts the amount of LED7 order to the peak voltage signal V ₁₀₂ to or higher than the threshold V _200.

Step S13: CPU 24 refers to the peak voltage signal V ₁₀₂ supplied from the signal processing unit 23 after adjusting, if the peak voltage signal V ₁₀₂ has been a threshold V ₂₀₀ or more, a defocus signal of the slit projection system proceeds is determined that can be satisfactorily produced (possible focus detection by the slit projection system) to step S14, if less than the threshold value V _200, it can not be satisfactorily generate the defocus signals slit projection system by (a slit projection type It is determined that focus detection is impossible), and the process proceeds to step S16.

Step S14: CPU 24, in order accommodate integrated signal supplied from the signal processing unit 23 V _R, the value of V _F within the allowable range, performing their integrated signal V _R, the gain adjustment of the V _F.

Step S15: CPU 24 is integrated signal V _R after the gain adjustment to produce a defocus signal of the slit projection system (V _F -V _R) by V _F, the polarity of the defocus signal (V _F -V _R) refer. If the polarity of the defocus signal (V _F −V _R ) is negative, the CPU 24 sets the driving direction of the first objective lens 3 upward, and the polarity of the defocus signal (V _F −V _R ) is If it is positive, the driving direction of the first objective lens 3 is set downward. Further, to set the absolute value of the drive speed of the first objective lens 3 to a large value V _72. This value V ₇₂ satisfy the relationship of _{V 74 <V 73 <V 72} .

Step S16: CPU 24, the charge accumulation time slower speed than the standard value (scanning time) (for example, 7 ms) to change the peak voltage signal V ₁₀₂ is the threshold value V ₂₀₀ supplied from the signal processing unit 23 after the change of the line sensor 22 If the was the above, and determined to be the focus detection slit projection type process proceeds to step S14, if less than the threshold value V _200, to step S17 it is determined that not the focus detection slit projection type move on.

  Step S17: The CPU 24 determines that the focal position of the first objective lens 3 is out of the adjustable range, and ends the flow. The above is the description of the flow of FIG.

The threshold values V ₇₀ , V ₇₁ , V ₂₀₀ , V ₂₀₂ and the values V ₇₂ , V ₇₃ , V _{74 described above} are determined in advance according to the type of the first objective lens 3 and the motor. In particular, the threshold value _V70 is determined according to the depth of focus of the first objective lens 3, and the value _V74 is determined according to the self-starting frequency of the motor.

  As described above, in the first focus adjustment mode, the CPU 24 of this embodiment repeatedly refers to the signal state of the contrast detection method during one focus adjustment period in which the defocus amount of the first objective lens 3 is driven to the depth of focus. (Steps S4 and S6) During the period in which focus detection by the contrast detection method is impossible (Step S4NO, Step S6NO), the first objective lens 3 is driven according to the polarity of the defocus signal of the slit projection method. (Steps S11 to S15) The first objective lens 3 is driven according to the polarity of the defocus signal of the contrast detection method during a period in which focus detection by the contrast detection method is possible (YES in Step S6).

  Therefore, if the focal position of the first objective lens 3 does not deviate from the adjustable range of the slit projection method, the CPU 24 of this embodiment performs the adjustment of the contrast detection method only once by performing the focus position search operation. Focus adjustment can be performed with accuracy.

  Next, the operation of the CPU 24 when the second focus adjustment mode is executed will be described. Here, the focus adjustment for the glass having the front surface and the back surface as the reflection surface will be described as an example.

  When focus adjustment is performed on a glass having a front surface and a back surface, reflected light returns from both the front surface and the back surface. Therefore, focus adjustment is performed so as to focus on an arbitrary surface closer to the local point among the front surface and the back surface. The second focus adjustment mode is a focus adjustment mode for avoiding such a problem.

  FIG. 10 is a diagram illustrating a state on the line sensor 22 of a slit image (reflected light image) from glass having a front surface and a back surface. FIG. 10A shows the state of the slit image when focused on the back surface, FIG. 10C shows the state of the slit image when focused on the front surface, and FIG. The state of the slit image when focused in the middle between the back surface and the back surface is shown. When focused on the back surface, as shown in FIG. 10 (a), it has a rectangular peak on the F side and a weak image on the R side. On the other hand, when focused on the surface, as shown in FIG. 10C, it has a rectangular peak on the R side and a weak image on the F side. Further, when focusing on the middle between the front surface and the back surface, as shown in FIG. 10B, there is a weak image on both the F side and the R side. In general, the reflected light on the front surface is stronger than the reflected light on the back surface, so the image on the F side is a little stronger.

  Here, consider a case where the back surface of the glass is selectively focused. In FIG. 10A, a position that equally divides the amount of received light corresponding to the slit image is defined as a reference position P1. In FIG. 10A, when the slit image is divided at the reference position P1, (F-side area Vx) = (R-side area Vy). Similarly, in FIGS. 10B and 10C, Vx ≠ Vy and Vx−Vy ≠ 0. Therefore, the back surface of the glass can be selectively focused based on the difference (Vx−Vy) between Vx and Vy.

  FIG. 11 shows (Vx−Vy) / (Vx + Vy) obtained by normalizing the above-described difference (Vx−Vy) and the defocus amount of the first objective lens 3 (the focal position of the first objective lens 3 and the sample surface). It is a figure which shows the relationship with 2a (shift of the optical axis direction). As shown in FIG. 11, (Vx−Vy) / (Vx + Vy) is zero only at the back surface position, and the focus is in the vicinity of the back surface no matter where the focus adjustment is started from any position other than the back surface position.

  FIG. 12 is a flowchart showing the operation of the CPU 24 when the second focus adjustment mode is executed. Below, the case where it selectively focuses on a back surface among a front surface and a back surface is demonstrated. The same can be applied to selectively focusing on the surface. The surface to be selectively focused is selected in advance by the user via an operation unit (not shown). Furthermore, it is good also as a structure which performs focus adjustment in order with respect to the front surface and the back surface. That is, the back surface is the second in-focus position. In the case of selectively focusing on the back surface, a reference position (reference position P1 described above) corresponding to the back surface is obtained in advance and recorded.

  In the following processing, focus adjustment is performed using only the slit projection method. That is, the present invention can also be applied to a focus adjustment apparatus having only a slit projection system (not having a contrast detection system).

  Steps S21 to S24: The same processing as Steps S1 to S4 in FIG. 9 is performed.

  Step S25: The CPU 24 calculates the absolute value | Vx−Vy | of the difference between Vx and Vy based on the reference position P1 corresponding to the back surface described above.

Step S26: CPU 24, the absolute value calculated in step S25 | Vx-Vy | determines whether less than a predetermined threshold value V _300. The threshold value _V300 is a predetermined threshold value, and can be estimated that the absolute value | Vx−Vy | is sufficiently close to zero, which is a value corresponding to the back surface, as shown in FIG. Absolute value of the difference between Vx and Vy | Vx-Vy | is, if not below the predetermined threshold value V _300, it is determined that not yet sufficiently close to the focus position proceeds to step S27. On the other hand, | Vx-Vy | When falls below a predetermined threshold value V _300, it is determined that close enough to focus position proceeds to step S28.

Step S27: The same processing as step S15 in FIG. 9 is performed. That is, the absolute value of the difference between Vx and Vy | Vx-Vy | is, to below the predetermined threshold value V _300, the absolute value | repeatedly performing operations and the driving of the first objective lens 3 | Vx-Vy.

  Step S28: The CPU 24 performs the focus adjustment of the slit projection method described in FIG.

Step S29: The CPU 24 determines whether or not the sample surface 2a is within the focal depth of the first objective lens 3 based on the slit projection type defocus signal (V _a −V _c ) / (V _a + V _c ). If it is determined and it is determined that it is within the depth of focus, the process proceeds to step S30.

  Step S30: The CPU 24 sets the driving speed of the first objective lens 3 to zero and ends the flow.

  Step S31: The same processing as step S15 in FIG. 9 is performed. That is, the slit projection type focus adjustment and the driving of the first objective lens 3 are repeatedly performed until the sample surface 2 a enters the depth of focus of the first objective lens 3.

  As described above with reference to the flowchart of FIG. 12, the focus adjustment is selectively performed on the back surface by performing the focus adjustment of the slit projection method based on the absolute value | Vx−Vy | of the difference between Vx and Vy. Can be burnt.

In the flow described with reference to FIG. 12, the case where the focus adjustment is performed based on the slit projection type defocus signal (V _a −V _c ) / (V _a + V _c ) has been described as an example. Focus adjustment may be performed using (Vx−Vy) as a defocus signal, or a slit projection type defocus signal (V _a −V _c ) / (V _a + V _c ) and a difference (Vx−Vy) are combined. You may adjust the focus.

  Next, a modified example of the second focus adjustment mode will be described using the flowchart of FIG. This modification is a focus adjustment method for switching between the slit projection method and the contrast detection method based on the difference (Vx−Vy).

  Steps S41 to S53: Processing similar to that in steps S1 to S13 in FIG. 9 is performed.

  Step S54: The CPU 24 calculates the absolute value | Vx−Vy | of the difference between Vx and Vy based on the reference position P1 corresponding to the back surface described above.

Step S55: CPU 24, the absolute value calculated in step S54 | Vx-Vy | determines whether less than a predetermined threshold value V _300. The threshold value _V300 is a predetermined threshold value, and can be estimated that the absolute value | Vx−Vy | is sufficiently close to zero, which is a value corresponding to the back surface, as shown in FIG. Absolute value of the difference between Vx and Vy | Vx-Vy | is, if not below the predetermined threshold value V ₃₀₀ is the focusing of it slit projection scheme determined not close enough to the back surface of the focus position Continue (return to step S54). On the other hand, the absolute value of the difference between Vx and Vy | Vx-Vy | When falls below a predetermined threshold value V _300, it is determined that sufficiently close to the back surface of the focus position, the step in order to switch the focusing of a contrast detection method Proceed to S56.

  Step S56 to Step S59: The same processing as Step S14 to Step S17 in FIG. 9 is performed.

  As described above with reference to the flow of FIG. 13, the absolute value | Vx−Vy | of the difference between Vx and Vy is used as a condition for switching the focus adjustment from the slit projection method to the contrast detection method. Can be in focus.

  Next, another modification of the second focus adjustment mode will be described using the flowchart of FIG. Similar to the modification described with reference to FIG. 13, this modification is another focus adjustment method that switches between the slit projection method and the contrast detection method based on the difference (Vx−Vy).

  Step S61 to Step S68: The same processing as Step S1 to Step S8 of FIG. 9 is performed.

  Step S69: The CPU 24 calculates the absolute value | Vx−Vy | of the difference between Vx and Vy based on the reference position P1 corresponding to the back surface described above.

Step S70: CPU 24, the absolute value calculated in step S69 | Vx-Vy | determines whether less than a predetermined threshold value V _300. The threshold value _V300 is a predetermined threshold value, and can be estimated that the absolute value | Vx−Vy | is sufficiently close to zero, which is a value corresponding to the back surface, as shown in FIG. Absolute value of the difference between Vx and Vy | Vx-Vy | is, if not below the predetermined threshold value V ₃₀₀ is has entered in-focus depth in step S68, the focus on the surface (surface) is not a back Therefore, the focus control is switched to the slit projection method (proceeding to step S73). On the other hand, the absolute value of the difference between Vx and Vy | Vx-Vy | When falls below a predetermined threshold value V _300, it is determined that focus on the back surface, the process proceeds to step S71.

  Step S71: The CPU 24 sets the driving speed of the first objective lens 3 to zero and ends the flow.

  Step S72: The CPU 24 sets the driving direction and the driving speed of the first objective lens 3 in the same manner as step S10 in FIG. 9, and returns to step S63.

  Step S73 to Step S79: The same processing as Step S11 to Step S17 of FIG. 9 is performed.

  As described above with reference to the flow of FIG. 14, after the focus adjustment is switched from the slit projection method to the contrast detection method, it is determined whether or not the focus adjustment is within the depth of focus by the contrast detection method. Further, by confirming whether or not the desired surface is focused based on the absolute value | Vx−Vy | of the difference between Vx and Vy, the back surface can be selectively focused.

  Finally, a case where the glass is thicker than that shown in FIG. 10 or a case where the magnification of the objective lens is higher than that shown in FIG. 10 will be described.

  A slit image (reflected light image) from a glass having a front surface and a back surface when the glass is thicker than that shown in FIG. 10 or when the magnification of the objective lens is higher than that shown in FIG. A state on the line sensor 22 is shown in FIG. 15A shows the state of the slit image when focused on the back surface, FIG. 15C shows the state of the slit image when focused on the front surface, and FIG. The state of the slit image when focused in the middle between the back surface and the back surface is shown.

  As shown in FIG. 15, when the glass is thicker than the case shown in FIG. 10, or when the magnification of the objective lens is higher than that shown in FIG. The slit image is separated. And as it separates, the slit image of the surface that is not in focus becomes weaker.

  Further, when the thickness of the glass is thicker or when the magnification of the objective lens is higher, only the slit image of the focused surface appears, and the slit image of the non-focused surface does not appear. . That is, when the back surface is focused, the slit image from the front surface is too blurred and does not appear as an output signal of the line sensor 22. Further, when focusing on the front surface, the slit image from the back surface is too blurred and does not appear as an output signal of the line sensor 22. And when the thickness of the glass is thicker or when the magnification of the objective lens is higher, this tendency becomes more prominent, and when focusing on the middle between the front surface and the back surface, the line sensor 22 The output signal does not appear.

Further, as shown in FIG. 15, when the thickness of the glass is thicker than that shown in FIG. 10, or when the magnification of the objective lens is higher than that shown in FIG. 10 (Vx−Vy). The relationship between / (Vx + Vy) and the defocus amount of the first objective lens 3 (corresponding to FIG. 11) is as shown in FIG. That is, two curves exist independently corresponding to each of the front surface and the back surface. This phenomenon is the same for the defocus signal (V _F −V _R ) and the defocus signal (V _a −V _c ) / (V _a + V _c ) shown in FIG. Then, two curves exist independently.

In such a case, the second focus adjustment mode described above may be modified as follows. The first method is a modified example described in the flow of FIG. 13, that is, first, focus adjustment is performed by the slit projection method. Then, the absolute value of the difference between Vx and Vy | Vx-Vy | When falls below a predetermined threshold value V _300, determines whether the focus adjustment is made to the desired surface. Absolute value of the difference between Vx and Vy | Vx-Vy |, the total of two times the surface and the back surface, below a predetermined threshold value V _300. Therefore, when focusing on the back from the front focus side by driving the first objective lens 3, the absolute value for the first time | focusing against the surface even below a predetermined threshold value V ₃₀₀ | Vx-Vy It can be determined that the focus adjustment is not performed on the desired surface. Accordingly, the first absolute value | Vx-Vy | when falls below a predetermined threshold value V ₃₀₀ is an amount corresponding first objective of glass thickness without going to a contrast detection method (corresponding to the distance between the surface and the back surface) The lens 3 is driven and adjusted to the vicinity of the back surface. Then, again performs focus adjustment of the projected slit type, then (second time) the absolute value | Vx-Vy | is When lower than a predetermined threshold value V _300, the process proceeds to a contrast detection method. Incidentally, in the case of driving the first objective lens 3 from the rear focus side, the absolute value | Vx-Vy | is lower than a predetermined threshold value V ₃₀₀ for the first time at the back side near a predetermined threshold value a second time near the surface V _{Below 300} . Accordingly, the first absolute value | Vx-Vy | may be determined that the focus adjustment is made to the desired surface Once below a predetermined threshold value V _300. Further, the above control may be executed by a contrast detection method.

  The second method is a modified example described in the flow of FIG. 14, that is, after the first objective lens 3 is driven from the front pin side and the focus adjustment is switched from the slit projection method to the contrast detection method. If it is determined that the depth of focus has been entered (S70 YES), the first objective lens 3 is driven by the glass thickness (corresponding to the distance between the front surface and the back surface), and is adjusted to the vicinity of the back surface. This is because the focus adjustment is performed on the surface when it is determined for the first time that the depth of focus is entered (S70 YES). Then, the focus adjustment of the contrast detection method is performed again, and if it is determined that it has entered the depth of focus again (S70 YES), it is determined that the back surface is in focus, and the driving speed of the first objective lens 3 is set to zero. End the process. In this process, the back surface can be selectively focused without using the absolute value | Vx−Vy | of the difference between Vx and Vy. When the first objective lens 3 is driven from the rear pin side, if it is determined that the first depth of focus is entered (S70 YES), it may be determined that focus adjustment is performed on a desired surface. .

  The two methods described above are examples in which the back surface is selectively focused, but the processing may be performed in accordance with the same idea when it is desired to selectively focus on the front surface.

As described above, according to the present embodiment, it is possible to perform suitable focus adjustment on a transmissive object having a plurality of reflecting surfaces. In particular, when an object such as glass that is the subject of focus adjustment is moved in the XY direction to change the observation location, the in-focus position easily shifts due to deflection, thickness unevenness, stage flatness, etc. It is possible to prevent focusing on a surface that is not a surface.

  Further, the focus adjustment device of the present embodiment can be applied to an industrial or biological microscope device or the like. The configuration of the microscope apparatus is, for example, as shown in FIG. In FIG. 17, most of the focus adjustment device (the tip of the half mirror 16 shown in FIG. 1) is omitted.

  As shown in FIG. 17, the microscope apparatus includes a light source 31 that emits visible light for observation, an illumination optical system 32 that projects an image of the light source 31 onto the pupil of the first objective lens 3, and the illumination optical system 3. A half mirror 33 that guides visible light to the first objective lens 3, an observation optical system 34 that forms an image of visible light (observation light) from the specimen 2 captured by the first objective lens 3, and the observation optical system 34 are formed. An image sensor 35 that captures a visible image is provided. If the focus adjustment apparatus of this embodiment is applied to this microscope apparatus, it is possible to perform focus adjustment with a short required time while effectively using two types of focus detection methods, so that the performance of the microscope apparatus is also improved.

  In the focus adjustment apparatus of the present embodiment, the slit projection type focus detection optical system and the contrast detection type focus detection optical system share the light receiving side optical system, and the slit projection type signal and the contrast detection type signal are used. However, the light receiving side optical system may be made independent and the slit projection method signal and the contrast detection method signal may be generated simultaneously in parallel.

  Further, the focus detection optical system of the contrast detection method of the present embodiment generates a defocus signal having polarity based on the contrast of two types of images, but has no polarity based on the contrast of one type of image. May be generated. Incidentally, the focus adjustment by the defocus signal having no polarity is performed by, for example, a mountain climbing method.

  The contrast detection method of the present embodiment is an active method in which AF light is projected onto the sample 2 and a defocus signal is generated based on the AF light reflected by the sample 2. However, the AF light is applied to the sample 2. Instead of projecting light, a passive system that generates a defocus signal based on observation light from the specimen 2 may be used.

  In addition, the focus adjustment apparatus of the present embodiment employs a slit projection type focus detection optical system (the shape of the pattern projected onto the sample 2 is slit) as the pattern projection type focus detection optical system. The shape of the pattern to be projected may be replaced with another shape such as a dot shape. However, the slit shape has an advantage that the optical elements such as the line sensor 22 can be easily aligned.

It is a block diagram of a focus adjustment apparatus. It is a figure explaining the back pin state of a slit projection system. It is a figure explaining the focusing state of a slit projection system. It is a figure explaining the front pin state of a slit projection system. It is a figure which shows the relationship between a defocus amount and a defocus signal. It is a figure explaining the back pin state of a contrast detection system. It is a figure explaining the focus state of a contrast detection system. It is a figure explaining the front pin state of a contrast detection system. 6 is a flowchart of a first focus adjustment mode. It is a figure which shows the mode on the line sensor 22 of the slit image (reflected light image) from the glass which has a surface and a back surface. FIG. 6 is a diagram illustrating a relationship between (Vx−Vy) / (Vx + Vy) and a defocus amount of the first objective lens 3. It is a flowchart of the 2nd focus adjustment mode. It is a flowchart of the modification of a 2nd focus adjustment mode. It is a flowchart of another modification of a 2nd focus adjustment mode. It is another figure which shows the mode on the line sensor 22 of the slit image (reflected light image) from the glass which has a surface and a back surface. FIG. 6 is another diagram showing the relationship between (Vx−Vy) / (Vx + Vy) and the defocus amount of the first objective lens 3. It is a block diagram of the microscope apparatus which can apply a focus adjustment apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Stage, 2 ... Sample, 3 ... 1st objective lens, 4 ... Dichroic mirror, 7 ... LED, 8 ... Slit plate, 9 ... Collector lens, 10 ... Pupil mask, 11 ... Half mirror, 12 ... Collector lens, 13 ... Slit plate, 14 ... LED, 16 ... Half mirror, 17 ... Second objective lens, 18 ... 3-divided prism, 22 ... Line sensor, 23 ... Signal processing unit, 24 ... CPU, 25 ... Vertical motion drive unit, 26 ... LED switching part

Claims (7)

A focusing device that performs focusing on a transmissive object having a plurality of reflecting surfaces,
Pattern projection means for projecting a pattern onto the transmission object through a part of the pupil of the objective lens;
First light receiving means comprising a plurality of line-shaped focus detection light receiving elements for receiving a pattern image reflected from the transmission object;
Based on the output of the first light receiving means, the amount of lateral deviation of the pattern image is obtained, and based on the amount of lateral deviation, the deviation in the optical axis direction between the focal position of the objective lens and the imaging position of the transmission object is indicated. First detection means for generating a first defocus signal;
With respect to at least one of the plurality of reflecting surfaces, a reference position on the focus detection light-receiving element that equally divides the received light amount of the pattern image at the time of focusing in the lateral shift direction of the pattern image is stored in advance. Determining means for determining whether focus adjustment is performed on a desired surface among the plurality of reflection surfaces based on an output signal of the light receiving element for focus detection and the reference position;
A first evaluation value indicating the quality of the first defocus signal is monitored, the evaluation value exceeds a first threshold value, and focus adjustment is performed on the desired surface by the determination unit. A focus adjustment device comprising: an adjustment unit that adjusts a distance between the objective lens and the transmission object based on the first defocus signal. The focus adjustment apparatus according to claim 1,
Second light receiving means comprising a plurality of line-shaped focus detection light receiving elements for receiving a pattern image reflected from the transmission object;
Based on the contrast amount of the pattern image received by the second light receiving means, a second defocus signal that indicates a deviation in the optical axis direction between the focal position of the objective lens and the imaging position of the transmission object is generated. 2 detecting means,
The focus adjustment apparatus, wherein the adjustment unit performs the interval adjustment based on at least one of the first defocus signal and the second defocus signal. The focusing apparatus according to claim 2, wherein
The adjusting means is
When the first evaluation value exceeds the first threshold value and the determination unit determines that focus adjustment is not performed on the desired surface, the first defocus signal is Based on the interval adjustment,
The first evaluation value exceeds the first threshold value, and it is determined by the determination means that focus adjustment is performed on the desired surface, and the quality of the second defocus signal is determined. When the second evaluation value shown exceeds the second threshold value, the interval adjustment is performed based on the second defocus signal. The focusing apparatus according to claim 2, wherein
The adjusting means is
When the second evaluation value indicating the quality of the second defocus signal exceeds the second threshold, the interval adjustment is performed based on the second defocus signal,
It is determined whether or not the in-focus state is approached based on the second defocus signal. When it is determined that the in-focus state is approached, the first evaluation value is monitored, and the first evaluation value is If the threshold value of 1 is exceeded and the determination means determines that focus adjustment is not performed on the desired surface, the determination means performs focus adjustment on the desired surface. Performing the interval adjustment based on the first defocus signal until it is determined that
The focus adjustment apparatus, wherein when the determination unit determines that focus adjustment is performed on the desired surface, the interval adjustment is performed based on the second defocus signal. The focusing apparatus according to claim 2, wherein
In a state in which any one of the plurality of reflective surfaces is in focus, the image processing device further includes a reception unit that receives in advance a user operation for designating the surface as the desired surface,
When the determination unit determines that focus adjustment is not performed on the desired surface specified by the reception unit, the adjustment unit applies the adjustment to the desired surface. Performing the interval adjustment based on the first defocus signal until it is determined that the focus adjustment is performed,
The focus adjustment apparatus, wherein when the determination unit determines that focus adjustment is performed on the desired surface, the interval adjustment is performed based on the second defocus signal. The focusing apparatus according to claim 2, wherein
In a state away from the in-focus state, the apparatus further comprises an accepting unit that accepts in advance a user operation that designates what number the desired surface is out of the plurality of reflective surfaces;
The adjusting means determines whether or not the in-focus state is approached based on the second defocus signal, and determines that the in-focus state is approached, and counts the number of times that the in-focus state is approached. When the number matches the designated content designated by the accepting means, the interval adjustment is performed based on the second defocus signal. A microscope optical system for observing an image captured by the objective lens;
A microscope apparatus comprising: the focus adjustment apparatus according to claim 1, wherein the focus adjustment of the objective lens is performed.

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