JP5289792B2 - Focus detection device and fluorescence observation device using the same - Google Patents

Description

  The present invention relates to a focus detection apparatus and a fluorescence observation apparatus using the focus detection apparatus, and in particular, in a microscope or an optical apparatus that performs fluorescence observation of living cells with high contrast, a glass surface on which an observation specimen to be observed and an observation specimen are mounted. The present invention relates to an apparatus capable of detecting an interface position with high accuracy.

  In the biological research field, functions and structures of cells are analyzed using fluorescence observation methods. However, in normal fluorescence observation, illumination light is irradiated to the entire observation object, and therefore fluorescence information other than the position where the observation is desired (the position where the focus is not in focus) is also acquired at the same time. For this reason, the contrast is lowered, and it is impossible to observe a minute unit such as one molecule.

  In recent years, the evanescent light generated at the time of total reflection of light is used as illumination light, and a technology for illuminating only a small region of several tens to several hundreds of nanometers has been established. It is possible to observe the fluorescence of minute units at the level of one molecule while preventing the decrease.

  The evanescent light is light generated by totally reflecting the illumination light when the illumination light is incident on the boundary surfaces having different refractive indexes at an angle of a certain value or less. In addition, evanescent light has the property of not propagating in free space, which is localized in a region having a size smaller than the wavelength, on the opposite side of the boundary surface from the illumination light.

  In biological research, a technique often referred to as time-lapse is used to observe changes over time in living cells. This method is intended to analyze the function inside the cell by acquiring observation images continuously or at regular intervals within a period of, for example, 1 day or 2 days.

  Although this method requires observation over a long period of time, the microscope, which is an observation device, is an aggregate of metal and glass. For example, even if the internal temperature of the room in which the experiment is performed changes slightly, the microscope deforms. The problem that the focus position shifts occurs. In particular, fluorescence observation using evanescent light for observing a minute region of several tens to several hundreds of nm is a big problem.

  Patent Document 1 discloses means for detecting the position of a part of cells existing in an evanescent field with high accuracy by using evanescent light dedicated to focus detection.

As shown in FIG. 11, the focus detection laser beam 90 is incident so as to be totally reflected at the interface 91a between the cover glass 91 and the observation sample 92 in the sample solution 96, and the evanescent light is leached into the cover glass surface. Let The observation specimen 92 located in the region where the evanescent light exists, that is, the evanescent field, generates scattered light 93 by the evanescent light. The scattered light 93 is collected by the objective lens 94, detected by the light receiving element 95, and the position having the highest received light intensity is set as the in-focus position. The focal position of the objective lens 94 is controlled from this position information. There is another light source for fluorescence observation of the sample, and the laser light 90 for focus detection can reduce damage to cells by using infrared light.
JP 2003-270524 A

  However, in the invention described in Patent Document 1, since the scattered light intensity by the cell is detected, the focusing accuracy and position are shaken depending on the number and state of the cells, and the scattered light intensity change at the time of focus adjustment is minute. The detection accuracy is expected to deteriorate.

  In addition, since the reference point used for focusing is a part of the sample that generates scattered light, when a living cell or the like is used as the observation sample, a part of the observation sample that generates the scattered light using the reference point is used. It is expected to move, and the focus adjustment will not be determined. For example, when a part of the cell used for focus adjustment moves upward and the actually observed part does not move, the observed part becomes out of focus.

  An object of the present invention is to achieve high focusing accuracy without affecting the state of a cell as a sample in high contrast fluorescence observation using evanescent light.

The focus detection apparatus of the present invention includes an objective lens for observing an observation specimen, a transparent member having a refractive index different from the refractive index of the observation specimen, and a light source having a predetermined wavelength for exciting the observation specimen. When the illumination light from the light source, an illumination optical system that emits through the outer peripheral portion of the objective lens so as to totally reflected at the boundary surface between the transparent member and the observation specimen, the reflected light is totally reflected by the boundary surface Detector through the objective lens, an observation optical system for performing fluorescence observation of the observation specimen with evanescent light generated when illumination light from the light source is totally reflected on the boundary surface, and the observation optical system An imaging optical system that is provided with respect to the optical axis and collects reflected light that is totally reflected on the boundary surface by illumination light from the light source , on the detection surface of the detector, and the boundary that the detector detects all anti-in surface Based on the focusing position of the reflected light, it said and said observation specimen and the objective lens are moved relative, characterized by comprising a control unit that performs focus adjustment of the objective lens.

  According to the present invention, high focusing accuracy can be realized without affecting the state of a cell as a sample.

  Embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of the fluorescence observation apparatus according to the first embodiment of the present invention. In the first embodiment and the following embodiments, an embodiment of the present invention will be described using an inverted epifluorescence microscope as a fluorescence observation apparatus.
In FIG. 1, reference numeral 1 denotes a microscope main body. The microscope main body 1 is similar to a general inverted epi-illumination fluorescent microscope, and includes an illumination unit 2, a dichroic mirror 3, an objective lens 4, a half mirror 5, an optical filter 6, and An image sensor (CCD camera or the like) 7 serving as an optical detector is provided, and these are arranged with their optical axes aligned.

  The illumination unit 2 includes an irradiation light source 8 that emits a laser beam having a predetermined wavelength that excites a specimen (viable cell) 12 to be described later, and a condensing lens 9 so that their optical axes coincide with each other. Further, the laser light from the irradiation light source 8 is adjusted so as to be condensed at the rear focal position of the objective lens 4 through the condenser lens 9 and the dichroic mirror 3.

  The dichroic mirror 3 is set to reflect the light having the wavelength of the illumination light 111 having a predetermined wavelength from the irradiation light source 8 and to transmit the wavelength of the fluorescence 112 having a longer wavelength than the illumination light 111 to be described later. The objective lens 4 is composed of an oil immersion objective lens having a high numerical aperture satisfying the condition of NA (numerical aperture of objective lens)> n (refractive index of observation specimen).

  A specimen 12 is disposed above the objective lens 4. The specimen 12 is brought into close contact with a cover glass 13 placed on a stage (not shown) of the microscope body 1. The cover glass 13 is filled with an aqueous solution necessary for the biological activity of the specimen 12 which is a living cell. The sample 12 is positioned at the focal position of the objective lens 4 through oil 15 having a refractive index substantially the same as the refractive index of the cover glass 13.

  The laser light of the irradiation light source 8 reflected by the dichroic mirror 3 is incident on the objective lens 4 as illumination light (excitation light) 111 with a small beam diameter passing through the outer peripheral portion of the objective lens 4 and totally reflected by the cover glass 13. The incident angle is adjusted, and evanescent light 17 is generated on the specimen 12 side when totally reflected by the cover glass 13. The evanescent light 17 is localized on the sample 12 side of the cover glass 13 at a distance shorter than the wavelength of the illumination light. After the illumination light 111 is totally reflected by the cover glass 13, the illumination light 111 is condensed at the back focal position of the objective lens 4 that is axially symmetric with the illumination light 111 with respect to the central axis of the objective lens 4, and is returned by the dichroic mirror 3. The light is reflected and shielded from the inner surface of the microscope body 1.

  On the other hand, weak fluorescence 112 (denoted by a broken line) emitted from the specimen 12 excited by the evanescent light 17 passes through the dichroic mirror 3 and enters the half mirror 5 via the optical filter 6. The half mirror 5 can be inserted into and removed from the observation optical axis. When the half mirror 5 is inserted into the optical axis, the fluorescence 112 is divided, one of the divided fluorescence becomes observable through the eyepiece 16, and the other divided fluorescence enters the image sensor 7. On the other hand, when the half mirror 5 is removed from the optical axis, all the fluorescence 112 is guided to the image sensor 7.

  The optical filter 6 constitutes an observation optical system together with the dichroic mirror 3 and the like, and can selectively pass light of a specific wavelength. Here, the light of the wavelength of the illumination light 111 is blocked and the light of the fluorescence 112 having a longer wavelength than the illumination light 111 is allowed to pass.

  The fluorescence 112 from the specimen 12 passes through the optical filter 6 and is observed as a fluorescence image by the eyepiece lens 16 and is imaged by the imaging element 7 via the imaging lens 18.

  The control unit 10 moves the focal position of the objective lens 4 in the optical axis direction by moving the objective lens 4 in the optical axis direction using the position control unit 14. Thereby, a plurality of fluorescent images of the fluorescence 112 are acquired by the image sensor 7 and the difference in contrast is obtained.

From this contrast difference, the position control unit 14 is controlled so that the focal position of the observation sample 12 and the objective lens 4 overlap, and the objective lens 4 is moved up and down.
Note that focus detection using a fluorescent image can be obtained not only from the contrast difference but also from the intensity distribution of the image.

With the above configuration, it is possible to perform focus detection and focusing using an image of the fluorescence 112 emitted from a part of the specimen 12 existing in a very thin evanescent light 17 region of several tens to several hundreds of nanometers.
The effect of high-precision focus detection combined with evanescent can be obtained. That is, since the fluorescence 112 emits light only in the region of the evanescent light 17 of the above several tens of nanometers to several hundreds of nanometers, focus detection can be performed with an accuracy of several tens of nanometers to several hundreds of nanometers.

  In addition, in a time lapse to see changes over time in living cells in biological research, observation over a long period of time is required, but the microscope, which is an observation device, is an aggregate of metal and glass, for example, in the room where the experiment is performed. Even with a slight change in internal temperature, the microscope is thermally deformed and the focus position is shifted. In particular, in fluorescence observation using evanescent light for observing a minute region such as tens to hundreds of nanometers, It has become a big problem. However, according to the present embodiment, since focus detection is performed using the image of the fluorescence 112 being observed, even if a microscope or the like undergoes thermal deformation, it is possible to continue observation while maintaining the focus for a long time. . Further, if a laser having a wavelength larger than that of the laser used for observation is separately prepared and used, the fading of fluorescence can be prevented.

  In the first embodiment and the following embodiments, an inverted epifluorescence microscope is used as the fluorescence observation apparatus. However, the present invention is not limited to this, and focusing is achieved using fluorescence. The present invention can be applied to any apparatus as long as it can be configured.

(Second Embodiment)
FIG. 2 is a diagram showing a schematic configuration of a fluorescence observation apparatus according to the second embodiment of the present invention. In FIG. 2, the same parts as those in FIG.
In the second embodiment, a condensing lens 30 and a detector 31 which are focus detection device systems are newly added to the optical axis of the observation optical system in the device in the first embodiment.
In FIG. 2, the return light 113 is shielded in the first embodiment. However, in this embodiment, the return light 113 is not shielded, and the detection point 37 of the detector 31 is detected by the condenser lens 30. Condensed backward.

The above configuration shows a configuration in which the contact surface of the cover glass 13 and the specimen 12 is coincident with the focal position of the objective lens 4, and the position 33 (dotted line) of the cover glass 13 is lower than the focal position of the objective lens 4. The state where the cover glass has moved in the direction is shown. When the cover glass 13 moves to the position 33, the return light 113 of the illumination light 111 moves to the position of the return light 123. Specifically, as shown in FIG. 2, since the reflecting surface of the illumination light 111 has moved downward, the optical path of the return light 123 moves to the optical path closer to the optical axis than the return light 113, and the condenser lens 30. The condensing position by is moved from the detection point 37 to the detection point 38.
Considering the case where the cover glass surface 13 moves upward from the focal position of the objective lens 4, the return light of the illumination light 111 passes through an optical path (not shown) opposite to the detection point 38 with respect to the detection point 37. become.
Therefore, first, the position of the detection point 37 of the detector 31 which is the condensing position by the condensing lens 30 in a state where the focus is achieved is stored. Since the focus is shifted when the condensing position is deviated from the detection point 37, the objective lens 4 is moved to return the condensing position to the position of the detection point 37 that is in focus. .

  As described above, the focus position of the objective lens 4 can be obtained by detecting the focus position of the return light with respect to the detector 31 and matching the focus position with the detection point at the time of focusing. . As a result, similarly to the first embodiment, even if a microscope or the like is thermally deformed, it is possible to continue observation while keeping the focus for a long time.

  The position of the detection point of the return light collected on the detector 31 indicates whether the contact surface of the cover glass 13 and the specimen 12 is in the upper or lower direction in the optical axis direction with respect to the focal position. Therefore, the adjustment direction during focus adjustment can be determined in a short time.

In the present embodiment, when it is desired to focus the objective lens 4 at a position different from the contact surface between the cover glass 13 and the specimen 12 (here, the contact surface between the cover glass surface 33 and the specimen), the return light detection point 38 is focused. You may offset as a coincidence point. If the illumination light 111 is condensed at the pupil position of the objective lens 4, the evanescent light 36 does not change.
Thereby, in addition to the above effect, it is possible to detect the focal position while keeping the focal point of the objective lens 4 offset at a position different from the contact surface between the cover glass 13 and the specimen 12.

Further, the illumination light 111 can change the penetration depth of the evanescent light 17 depending on the incident angle to the cover glass surface 13, but the detection point after the penetration depth of the evanescent light 17 is changed. May be offset as a focus coincidence point.
Thereby, in addition to the above effect, the focal position can be detected even if the penetration depth of the evanescent light 17 is changed.

Further, the incident angle of the illumination light 111 on the cover glass surface 13 may be changed during a short period of time when the cover glass surface 13 does not move, and the change amount of the detection point of the return light may be read.
Thereby, the amount of change in the penetration depth of the evanescent light 17 can be obtained.

As shown in FIG. 3, instead of the surface sensor and line sensor that are the detector 31 shown in FIG. 2, a condensing point detector 41 combining a pinhole 39 and a light detector 40 may be used. In this case, in order to detect a condensing position, the condensing point detector 41 is moved and the condensing point is detected by the photodetector 40.
Thereby, in addition to the above effect, the expensive detector 31 can be replaced with a cheaper detector.

Alternatively, the illumination light 111 used for focus detection may be dedicated light for focus detection, and a light source for illumination may be arranged separately.
Thereby, in addition to the above effects, the wavelength of the light source for focus detection can be changed to infrared light or the like that hardly damages the specimen 12 that is a living body.

(Third embodiment)
FIG. 4 is a diagram showing a schematic configuration of a fluorescence observation apparatus according to the third embodiment of the present invention. In FIG. 4, the same parts as those in FIG.
As shown in FIG. 4, in this embodiment, a focus detection lens 50 that is a focus detection light source system, a focus detection lens 53 that is a focus detection device system, and a two-divided detector 54 are added to the observation optical system. It is added to the optical axis of the system.

In the present embodiment, the return light 113 is configured to be selectable between light shielding and transmission by the light shielding plate 52 that can be inserted and removed.
When the focus detection lens 50 is inserted into the illumination optical path, the light shielding plate 52 is removed from the optical path of the focus detection return light 132, and the focus detection return light 132 reaches the two-divided detector 54. On the other hand, when the focus detection lens 50 is removed from the illumination optical path, the light shielding plate 52 is inserted into the optical path of the return light 113 and the return light 113 is shielded.

  The focus detection lens 50 is disposed in a state where it can be inserted and removed at a position that is beneficial to the focus of the condenser lens 9. When the focus detection lens 50 is inserted into the illumination optical path, the illumination light 111 becomes the focus detection light 131. The laser light incident on the objective lens 4 as the focus detection light 131 is reflected at the same time as being focused on the contact surface between the cover glass 13 and the specimen 12, and is axially symmetric with the focus detection light 131 with respect to the central axis of the objective lens 4. Focus detection return light 132. The focus detection return light 132 is reflected by the dichroic mirror 3.

  The focus detection return light 132 reflected by the dichroic mirror 3 is collected by the focus detection lens 53 whose optical axis coincides with the focus detection optical axis, and is output from the two-divided detector 54 whose axis coincides with the focus detection optical axis. Focus at the center split. At this time, on the condensing surface 55 of the two-divided detector 54, small condensed light straddling both detection elements of the two-divided detector 54 is observed.

The split surface of the two-split detector 54 is configured to be parallel to the optical axis and perpendicular to the plane including the axes of the focus detection light 131 and the focus detection return light 132. Here, as shown in FIG. 5, when the contact surface of the cover glass 13 and the specimen 12 moves downward, the laser light incident on the objective lens 4 as the focus detection light 131 is the boundary between the cover glass 13 and the specimen 12. The focus detection return light 133 is reflected without focusing on the surface. The focus detection return light 133 arrives at a position deviated from the center of the two-divided detector 54 without being condensed. Therefore, a large blur light 56 that is biased toward one element of the two-divided detector 54 is observed on the condensing surface 55 of the two-divided detector 54. On the contrary, when the contact surface of the cover glass 13 and the specimen moves upward as shown in FIG. 6, large blur light 57 biased to the opposite element of the two-divided detector 54 is observed.
Therefore, focus adjustment can be performed by adjusting the objective lens in the optical axis direction so that small condensed light straddling both detection elements can be observed on the condensing surface 55 of the two-divided detector 54.

  As described above, according to the present embodiment, it is possible to detect the focal position of the objective lens 4 while periodically switching the illumination light 111 to the focus detection light 131. As a result, similarly to the first embodiment, even if a microscope or the like is thermally deformed, it is possible to continue observation while keeping the focus for a long time. Further, since the illumination light is diverted to the focus detection light, the overall configuration becomes simple and can be configured at low cost. Further, since the focus detection light can be switched to illumination light only when necessary, damage to specimens such as living cells is reduced. Also in focus detection, it can be determined whether the cover glass 13 is in the upper or lower direction of the focal plane depending on which of the condensing surfaces of the two-divided detector 54 the focus detection return light 132 has reached. The moving direction of the cover glass 13 can be determined only by this.

(Fourth embodiment)
FIG. 7 is a diagram showing a schematic configuration of a fluorescence observation apparatus according to the fourth embodiment of the present invention. In FIG. 7, the same parts as those in FIG.
As shown in FIG. 7, in the present embodiment, a focus detection light source 60, which is a new focus detection light source system, a collimator lens 61, a light shielding plate 62, a semi-transmissive mirror 63, a focus detection dichroic mirror 69, and A focus detection lens 64, which is a focus detection device system, a wavelength cut plate 70, and a two-divided detector 65 are added to the optical axis of the observation optical system.

  In FIG. 7, the illumination system and the observation system are the same as the configuration according to the first embodiment. The dichroic mirror 3 reflects the light having the wavelength of the illumination light 111 having a predetermined wavelength from the irradiation light source 8 and transmits the weak fluorescent light having a long wavelength emitted from the sample 12 by the excitation of the illumination light 111. The focus detection light 141 used for focus detection having a wavelength longer than the wavelength is also set to be transmitted.

  In the illumination system, the return light 113 totally reflected by the cover glass 13 is prevented from leaking to the observation optical system, and the light shielding plate 71 is disposed on the sample side from the dichroic mirror 3.

  In the focus detection system, a focus detection light source 60 that emits laser light of a predetermined wavelength in the infrared region that hardly damages living cells, and a collimator lens 61 are arranged so that their optical axes coincide with each other. Each is adjusted so that the laser light from the focus detection light source 60 is condensed at the focal position of the objective lens 4 via the collimating lens 61, the semi-transmissive mirror 63, the focus detection light dichroic mirror 69, and the dichroic mirror 3. .

The semi-transmissive mirror 63 is set so as to semi-transmit the laser light having a predetermined wavelength from the focus detection light source 60 and reflect the remaining half of the light amount.
The focus detection light dichroic mirror 69 is set to transmit the fluorescence wavelength and reflect the focus detection light 141 having a wavelength longer than that of the fluorescence.

The laser light from the focus detection light source 60 is incident on the objective lens 4 as focus detection light 141 whose half is shielded by the light shielding plate 62 disposed at the pupil position of the collimator lens 61, and the cover glass 13 and the specimen 12 are in close contact with each other. The focal point is focused and reflected to become focus detection return light 142 that is symmetrical with the focus detection light 141 with respect to the central axis of the objective lens 4.
The light shielding plate 62 shields the semicircular portion of the disk-shaped glass plate and transmits the rest so as to shield it in a semicircular shape when viewed from the cross section of the focus detection light.

The focus detection return light 142 reflected by the contact surface between the cover glass 13 and the specimen 12 is transmitted through the dichroic mirror 3, reflected by the focus detection dichroic mirror 69, and half of the light quantity is reflected by the semi-transmissive mirror 63 to block the light. The light is shielded by the plate 62 and the remaining half of the light is transmitted. The focus detection return light 142 transmitted through the semi-transmissive mirror 63 is collected by the focus detection lens 64 whose optical axis coincides with the focus detection optical axis, and only the wavelength of the focus detection light source 60 is transmitted by the wavelength cut plate 70. Then, the focal point is formed at the central divided portion of the two-divided detector 65 whose axis coincides with the focus detection optical axis. At this time, on the condensing surface 66 of the two-divided detector 65, small condensed light straddling both detection elements of the two-divided detector 65 is observed.
The split surface of the two-split detector 65 is configured in the same plane as the plane parallel to the optical axis and including the split lines of the focus detection light 141 and the focus detection return light 142.

  As a result, it is possible to detect a state in which the objective lens 4 is focused on the contact surface of the cover glass 13 and the specimen 12.

  In FIG. 8, when the cover glass 13 moves downward, the laser light incident on the objective lens 4 as the focus detection light 141 is reflected without being focused on the contact surface between the cover glass 13 and the specimen 12, and the objective lens. Even if it passes through 4, it becomes the focus detection return light 143 which is not collimator light. The focus detection return light 143 is guided to the two-divided detector 65 and arrives at a position deviated from the center of the two-divided detector 65 without being condensed. Therefore, a large blur light 67 that is biased toward one element of the two-divided detector 65 is observed on the condensing surface 66 of the two-divided detector 65. Conversely, when the cover glass 13 moves upward as shown in FIG. 9, a large blur light 68 biased to an element opposite to the detection element of the two-split detector 65 when the cover glass 13 moves downward. Is observed.

  As described above, the focus adjustment is performed by adjusting the objective lens in the optical axis direction so that small condensed light straddling both detection elements can be observed on the condensing surface of the focus detector.

  According to the present embodiment, it is possible to always detect the focal position of the objective lens while observing the fluorescent image. Further, since the light sources of the illumination light 111 and the focus detection light 141 are different, infrared light or the like is used as the focus detection light 141, and damage to a specimen such as a living cell can be reduced. Also in focus detection, it can be determined whether the cover glass 13 is in the upward or downward direction of the focal plane depending on which of the condensing surfaces of the two-divided detector 65 the focus detection return light 142 has reached. The moving direction of the cover glass 13 can be determined only by this when adjusting the focus. Furthermore, even if the incident angle of the illumination light 111 to the cover glass 13 is changed and the penetration depth of the evanescent light 17 is changed, the focus detection is performed with a completely different light source, so that the focus detection is not affected. Similarly to the first embodiment, even if a microscope or the like undergoes thermal deformation, it is possible to continue observation while keeping the focus for a long time. Further, by offsetting the focus coincidence position in the two-divided detector 65, focus detection can be performed while observing the image even if the focal position of the objective lens 4 is away from the contact surface of the cover glass 13 and the specimen 12.

(Fifth embodiment)
FIG. 10 is a diagram showing a schematic configuration of a fluorescence observation apparatus according to the fifth embodiment of the present invention. 10, the same parts as those in FIG. 1 are denoted by the same reference numerals.

  In FIG. 10, reference numeral 1 denotes a microscope main body. The microscope main body 1 is similar to a general inverted epi-illumination fluorescent microscope, and includes an illumination light source 84, an objective lens 4, a dichroic mirror 3, an optical filter 6, a half mirror 5, and The image sensor 7 as a light detector, a focus detection light source 87, and a focus detection device 89 are provided and are arranged with their optical axes aligned. Illumination light from the illumination light source 84 irradiates the specimen 12 through an excitation filter 85 that transmits only light of a predetermined wavelength that excites the specimen 12. The objective lens 4 is composed of an oil immersion objective lens having a high numerical aperture satisfying the condition of NA (numerical aperture of objective lens)> n (refractive index of observation specimen).

  A specimen 12 is disposed above the objective lens 4. The specimen 12 is brought into close contact with a cover glass 13 placed on a stage (not shown) of the microscope body 1. The cover glass 13 is filled with an aqueous solution necessary for the biological activity of the specimen 12 which is a living cell. The sample 12 is positioned at the focal position of the objective lens 4 through oil 15 having a refractive index substantially the same as the refractive index of the cover glass 13.

  The weak fluorescence 112 emitted from the specimen 12 by excitation of the illumination light 88 is transmitted through the objective lens 4 and the dichroic mirror 3 and is incident on the half mirror 5 through the optical filter 6. The half mirror 5 can be inserted into and removed from the observation optical axis. When the half mirror 5 is inserted into the optical axis, the fluorescent light 112 is divided, and one divided fluorescent light can be observed through the eyepiece 16. The other divided fluorescence enters the image sensor 7. On the other hand, when the half mirror 5 is removed from the optical axis, all the fluorescence 112 is guided to the image sensor 7. The optical filter 6 constitutes an observation optical system together with the dichroic mirror 3 and the like, and can selectively pass light of a specific wavelength. Here, as the optical filter 6, an optical filter that blocks the light with the wavelength of the illumination light 88 and the light with the wavelength of the focus detection light 151 and passes the light of the fluorescence 112 having a longer wavelength than the illumination light 88 is used. The fluorescence 112 from the specimen 12 passes through the optical filter 6 and is observed as a fluorescence image and is imaged by the image sensor 7.

  In the focus detection system, a focus detection light source 87 and a condensing lens 86 that emit laser light having a predetermined wavelength in the infrared region that do not easily damage a specimen that is a living cell are arranged so that their optical axes coincide with each other. The laser light from the focus detection light source 87 is adjusted so as to be condensed at the rear focal position of the objective lens 4 via the condenser lens 86 and the dichroic mirror 3.

The dichroic mirror 3 transmits the fluorescence wavelength longer than the excitation light 88, reflects the focus detection light 151 having a predetermined wavelength in the infrared region from the focus detection light source 87, and does not pass the excitation light 88. Has been.
The laser beam of the focus detection light source 87 reflected by the dichroic mirror 3 is irradiated on the specimen 12 through the objective lens 4 as focus detection light 151.

  The focus detection light 151 has a small beam diameter that passes through the outer peripheral portion of the objective lens 4 and is adjusted to an incident angle at which the cover glass 13 and the sample 12 are totally reflected. Evanescent light 17 is generated on the specimen 12 side when totally reflected. The evanescent light 17 is localized on the sample 12 side of the cover glass 13 at a distance shorter than the wavelength of the focus detection light 151. After the focus detection light 151 is totally reflected by the cover glass 13, the focus detection light 151 is condensed at the back focal position of the objective lens 4 that is axisymmetric to the focus detection light 151 with respect to the central axis of the objective lens 4. The light is reflected by the dichroic mirror 3 and shielded from the inner surface of the microscope body 1.

When the evanescent light 17 hits the specimen 12, the scattered light 161 is generated. The scattered light 161 is reflected by the dichroic mirror 3 and enters the focus detection device 89.
The focus detection device 89 includes a condenser lens 80, a pinhole 81, a filter 82, and a detector 83, each of which coincides with the optical axis of the microscope body 1. The scattered light 161 is condensed on the detector 83 by the condenser lens 80. A pinhole 81 is arranged at the pupil position of the condensing lens 80, and significantly cuts unnecessary rays other than the scattered light 114 at the center of the visual field to be focused. Between the pinhole 81 and the detector 83, a filter 82 that transmits only the wavelength of the scattered light 161, which is a predetermined wavelength in the infrared region, and removes other wavelengths such as the illumination light 88 is configured.

  In the control unit 10, the objective lens 4 is moved in the optical axis direction by using the position adjusting unit 14, and thereby the focal position of the objective lens 4 is moved in the optical axis direction, whereby a plurality of images of the scattered light 161 are detected by the detector 83. To obtain the difference in signal strength. From this signal intensity difference, the state where the signal intensity is maximized is the state where the focal position of the specimen 12 and the objective lens 4 overlaps, and the position control unit 14 is controlled to bring the objective lens 4 to the position where the signal intensity is maximized. Move in the direction of the optical axis.

According to the present embodiment, focus detection and focusing are performed using an image of scattered light 161 emitted from a part of the specimen 12 existing in a very thin evanescent light 17 region of several tens to several hundreds of nanometers. It becomes possible.
Since the scattered light 161 emits light only in the region of the evanescent light 17 of several tens of nanometers to several hundreds of nanometers as described above, focus detection with an accuracy of several tens of nanometers to several hundreds of nanometers can be obtained as an effect. .

  In addition, in a time lapse to see changes over time in living cells in biological research, observation over a long period of time is required, but the microscope, which is an observation device, is an aggregate of metal and glass, for example, in the room where the experiment is performed. Even with a slight change in internal temperature, the microscope is thermally deformed and the focus position is shifted. In particular, in fluorescence observation using evanescent light for observing a minute region such as tens to hundreds of nanometers, It has become a big problem. However, in this embodiment, since focus detection is performed using the scattered light of the specimen being observed, observation can be continued with the focus kept on for a long time even if the microscope or the like undergoes thermal deformation. In addition, since only an image of a portion to be focused is selected by the pinhole 81, an image unrelated to the focus can be removed, and the accuracy of focus detection can be improved.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation. For example, in each of the above embodiments, the focus detection methods have been described individually, but it is needless to say that they can be combined as appropriate. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.

  In addition, for example, even if some structural requirements are deleted from all the structural requirements shown in each embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the effect of the invention Can be obtained as an invention.

The figure which shows schematic structure of the fluorescence observation apparatus concerning the 1st Embodiment of this invention. The figure which shows schematic structure of the fluorescence observation apparatus concerning the 2nd Embodiment of this invention. The figure which shows schematic structure of the fluorescence observation apparatus concerning the modification of the 2nd Embodiment of this invention. The figure which shows schematic structure of the fluorescence observation apparatus concerning the 3rd Embodiment of this invention. In the 3rd Embodiment of this invention, the figure which shows the detection position of the focus detection return light when the contact | adherence surface of a cover glass and a sample moves below. In the 3rd Embodiment of this invention, the figure which shows the detection position of the focus detection return light when the contact | adherence surface of a cover glass and a specimen moves to the upper direction. The figure which shows schematic structure of the fluorescence observation apparatus concerning the 4th Embodiment of this invention. The figure which shows the detection position of the focus detection return light when the contact | adherence surface of a cover glass and a sample moves below in the 4th Embodiment of this invention. In the 4th Embodiment of this invention, the figure which shows the detection position of a focus detection return light when the contact | adherence surface of a cover glass and a sample moves to the upper direction. The figure which shows schematic structure of the fluorescence observation apparatus concerning the 5th Embodiment of this invention. The figure which shows schematic structure of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Microscope main body 2 ... Illumination part 3 ... Dichroic mirror 4 ... Objective lens 5 ... Half mirror 6 ... Optical filter 7 ... Imaging element 8 ... Illumination light source 9 ... Condensing lens 10 ... Control part 12 ... Sample 13 ... Cover glass 14 ... Position control unit 15 ... Oil 16 ... Eyepiece 17 ... Evanescent light 18 ... Imaging lens 30 ... Condensing lens 31 ... Detector 32 ... Cover glass surface 36 ... Evanescent light 39 ... Pinhole 40 ... Photo detector 41 ... Condensing point Detector 50 ... Focus detection lens 52 ... Light-shielding plate 53 ... Focus detection lens 54 ... 2-divided detector 55 ... Condensing surface 60 ... Focus detection light source 61 ... Collimating lens 62 ... Light-shielding plate 63 ... Semi-transmissive mirror 64 ... Focus Lens for detection 65 ... Divided detector 66 ... Condensing surface 67 ... Blurred light 69 ... Dichroic mirror for focus detection 80 ... Collection Lens 81 ... pinhole 82 ... filter 83 ... detector 84 ... illumination light source 85 ... excitation filter 86 ... condenser lens 87 ... focus detection light sources 89 ... focus detection device

Claims (6)

An objective lens for observing the observation specimen;
A transparent member having a refractive index different from the refractive index of the observation specimen;
A light source having a predetermined wavelength for exciting the observation specimen;
The illumination light from the light source, an illumination optical system that emits through the outer peripheral portion of the objective lens so as to totally reflected at the boundary surface between the transparent member and the observation specimen,
A detector for detecting reflected light totally reflected at the boundary surface through the objective lens;
An observation optical system for performing fluorescence observation of the observation specimen by evanescent light generated when illumination light from the light source is totally reflected at the boundary surface;
An imaging optical system that is provided with respect to the optical axis of the observation optical system and collects reflected light totally reflected on the boundary surface by illumination light from the light source on the detection surface of the detector;
A control unit that adjusts the focus of the objective lens by relatively moving the objective lens and the observation specimen based on the condensing position of the reflected light totally reflected by the boundary surface detected by the detector;
A focus detection apparatus comprising:   The focus detection apparatus according to claim 1, wherein the illumination optical system includes a focus detection lens that condenses illumination light from the light source at a pupil position of the objective lens. The control unit changes the detection position when the boundary surface is the in-focus position to the condensing position when the position different from the boundary surface is the in-focus position, thereby changing the in-focus position to the boundary position. The focus detection apparatus according to claim 2 , wherein the focus detection apparatus is offset from the surface. A light shielding member that can be inserted into and removed from the optical path of the imaging optical system and shields the reflected light;
The focus detection lens can be inserted into and removed from the optical path of the illumination optical system, and the focus detection is performed by inserting the focus detection lens into the optical path and removing the light shielding member from the optical path, and the focus 3. The focus detection apparatus according to claim 2, wherein the detection lens can be switched from fluorescence observation in which the lens for detection is removed from the optical path and the light shielding member is inserted into the optical path to irradiate the observation specimen with evanescent light. The illumination optical system, a focus detection apparatus according to claim 1 to 4, wherein it is possible change the incident angle of the illumination light on the boundary surface. The illumination optical system, a focus detection apparatus of claims 1 to 5, wherein further comprising a dichroic mirror for reflecting the reflected light totally reflected from the illumination light and the boundary surface is emitted from the light source.

Images