JP2004013071A - Slit projection type autofocus device - Google Patents

Abstract

An object of the present invention is to provide a slit projection type autofocus apparatus which enables autofocus control of an observation object even when a lens which reflects slit-like illumination light at a central portion is used.
An illumination light from an LED light source is formed into a slit shape through a slit plate and is condensed and irradiated on a sample on a stage through a first objective lens, and the reflected light is transmitted through the first objective lens for autofocusing. In a slit projection type auto-focusing apparatus that forms an image with the CCD 30 and positions the specimen at the focus position of the first objective lens 12, a light-blocking filter 32 is disposed between the collector lens 32 and the first pupil restriction mask 24, By blocking the central portion of the illumination light, the reflection of the illumination light on the first objective lens 12 is suppressed, and the auto focus control operates normally.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a slit projection type autofocus device for a microscope used for observation of a sample (specimen).
[0002]
[Prior art]
A slit projection method is known as an autofocus (autofocus) device for a microscope. The slit projection method is a method of irradiating a sample with slit-shaped illumination and using the reflected light to adjust the sample to a focal point of an objective lens. Specifically, focusing is performed by the following method. An LED (light emitting diode) or the like is used as an auxiliary light source, and the light is passed through a slit to produce slit-like illumination light, and the slit-like illumination light is bisected along a center line extending in the longitudinal direction from the optical axis. Then, one is shielded from light, and the remaining illumination light is condensed and irradiated on the sample through the objective lens. The illumination light condensed and irradiated on the specimen is reflected by the specimen, passes through the objective lens, forms an image on a photoelectric converter such as a CCD sensor, is detected, and focus information (relative from the focus position of the objective lens) is obtained from the image. Target distance) is calculated. Based on this focus information, for example, control is performed to move the stage to a position in the optical axis direction, the distance between the objective lens and the sample is adjusted, and control is performed to a focused position.
[0003]
On the other hand, a biological microscope that mainly observes the specimen image by transmitting illumination light detects the contrast of the specimen image, finds the position where the contrast becomes maximum, and focuses on the image. However, this method has a problem that it takes a long time to extract the contrast of a light-colored sample or the like, and a slit projection type autofocus apparatus has been put to practical use.
[0004]
[Problems to be solved by the invention]
However, as described above, in a biological microscope, since illumination light is transmitted to a specimen and the light is used through an objective lens, no design has been made in consideration of light reflection at the objective lens. Was. Therefore, when the sample is irradiated with the slit illumination light through the objective lens, depending on the objective lens used (for example, a high-magnification lens for transmission illumination, particularly a liquid immersion type), the slit-shaped illumination at the central portion of the objective lens is used. Since the reflection of light is large and mixed with the reflected light from the sample, only the reflected light from the sample cannot be detected, and accurate autofocus control may not be performed.
[0005]
The problem of autofocus control obstruction in the slit projection type autofocus device due to the reflection of the objective lens can be counteracted by reducing the reflection at the center portion by designing the objective lens. In some cases, the objective performance is reduced. In addition, when such an objective lens is already used, if a countermeasure is taken with the objective lens, it is necessary to prepare an objective lens with a new countermeasure, and there is a problem that the cost burden is increased. Was.
[0006]
The present invention has been made in view of such a problem, and has a means for shielding a central portion of a slit-shaped illumination light, and observes even when a lens that reflects the slit-shaped illumination light at the central portion is used. It is an object of the present invention to provide a slit projection type autofocus device that enables autofocus control on an object.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a slit projection type autofocus apparatus according to the present invention includes a light source, a slit plate in which a slit is formed, and passing light from the light source through the slit plate. A focus illumination optical system for irradiating an object to form an image of the slit on the object, and a reflected image of the slit image by receiving reflected light of the image of the slit from the object through the objective lens A focusing imaging optical system that forms the image, a photoelectric converter that is provided at an imaging position of the reflection image by the focusing imaging optical system, and that detects the reflection image, and the photoelectric conversion device. Signal output means for outputting a signal for controlling the operation of the focus actuator based on the signal of the reflected image; and an image of the slit reflected by a central portion of the objective lens. Configured with a means for shielding for blocking light to be formed.
[0008]
In addition, it is preferable that the light-shielding unit is configured by a light-shielding plate that shields light that reflects at a central portion of the objective lens and forms an image of the slit.
[0009]
At this time, the light-shielding plate is provided in the focus illumination optical system, and is configured to block light forming a central portion of the image of the slit, or the light-shielding plate is provided for the focus. It is preferable that the optical system be arranged in the imaging optical system and configured to block light forming a central portion of the reflection image.
[0010]
Since the center of the objective lens, the focus illumination optical system, and the focus imaging optical system are disposed so as to be aligned with the optical axis, the light is reflected at the center of the objective lens to form an image of the slit. In order to shield the light, the light forming the central portion of the image of the slit or the reflected image is shielded.
[0011]
Further, it is preferable that a light shielding plate attaching / detaching means for attaching / detaching the light shielding plate is provided.
[0012]
Further, the light-shielding plate, the light-shielding plate attaching / detaching means for attaching and detaching the light-shielding plate according to the type of the objective lens detected by the detecting means, the light-shielding plate attaching / detaching means having detecting means for detecting the type of the object lens, Preferably, it is configured.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, before describing the slit projection type autofocus device according to the present invention, a microscope equipped with the slit projection type autofocus device will be described. This microscope forms an enlarged image of a specimen to be observed and is used for observation. The specimen (not shown) is placed on the stage 11 between the cover glass 14 and the slide glass 15.
[0014]
First, the optical system of the microscope will be described. The optical system of the microscope includes an observation optical system 3 arranged above the specimen, and a focusing illumination optical system 5 and a focusing image forming optical system 7 arranged beside the observation optical system 3.
[0015]
The focusing illumination optical system 5 is configured such that an LED light source 21, a slit plate 22, a collector lens 23, a first pupil restriction mask 24, and a first half mirror 25 are arranged in this order on the optical axis. As shown in FIG. 2 (a), a rectangular elongated slit opening 22a is formed in the center of the slit plate 22, and the slit plate 22 has a slit opening 22a as shown in FIG. 2 (b). It is arranged around the optical axis so that its longitudinal direction extends in the direction perpendicular to the paper of FIG. The infrared light emitted from the LED light source 21 enters the slit plate 22, passes through the slit opening 22 a of the slit plate 22, is converted into parallel light by the collector lens 23, and is irradiated on the first pupil restriction mask 24. The first pupil restriction mask 24 shields half of the pupil, and as shown in FIG. 2C, half of the pupil is shielded along the longitudinal center line of the slit-shaped illumination light around the optical axis. And the shape of the slit-shaped illumination light that has passed through the first pupil restriction mask 24 is as shown at 22b. The infrared light La that has passed through the first pupil restriction mask 24 passes through the first half mirror 25. The first half mirror 25 is provided at a point where the optical axes of the focusing illumination optical system 5 and the focusing image forming optical system 7 intersect, and reflects a part of the infrared light to form another half mirror. And is also used by the focusing imaging optical system 7 as described later. A dichroic mirror 16 is provided at a point where the optical axis of the focusing illumination optical system 5 and the optical axis of the observation optical system 3 intersect, and is shared by the observation optical system 3 as described later. The dichroic mirror 16 is disposed in an afocal system on the observation optical path of the observation optical system 3, and has a function of reflecting infrared light and transmitting visible light. The infrared light La transmitted through the first half mirror 25 irradiates the dichroic mirror 16 and is reflected downward (infrared light Lb), and is condensed and irradiated on the sample via the first objective lens 12. The first objective lens 12 is shared by the observation optical system 3 as described later.
[0016]
The observation optical system 3 includes a first objective lens 12, a dichroic mirror 16, a second half mirror 17, and an eyepiece second objective lens 13 arranged in this order from the one closer to the specimen. An eyepiece (not shown) is provided at the end of the second objective lens 13. Although not shown, the microscope is provided with an illuminating device that illuminates the sample placed on the stage 11. This illumination device is of a transmission type or an epi-illumination type, and is arranged below the stage 11 in the case of a transmission type illumination device, and is arranged above the stage 11 in the case of an epi-illumination type illumination device. The visible light emitted from the illumination device passes through the sample, is converted into parallel light by the first objective lens 12, passes through the dichroic mirror 16, and enters the second half mirror 17. The second half mirror 17 reflects a part of the visible light and transmits another part, and the visible light incident on the second half mirror 17 is partially reflected and is An observation image of the specimen is formed by the two objective lens 13 and the eyepiece, and is provided for observation. A part of the visible light transmitted through the second half mirror 17 passes through the second objective lens 36 for the camera and the relay lens 37 and forms an image on the imaging surface of the CCD 38 for the camera. It can also be used for processing and projecting an image of the specimen on a monitor (not shown).
[0017]
Since the sample on the stage 11 is covered with the cover glass 14, the infrared light Lc formed by the first objective lens 12 is reflected on, for example, the surface of the cover glass 14 as shown in FIG. Light Ld). The infrared light Ld reflected by the surface of the cover glass 14 is converted into parallel light by the first objective lens 12 (infrared light Le), and is reflected laterally by the dichroic mirror 16 (infrared light Lf). The light enters the first half mirror 25.
[0018]
The infrared light Lf incident on the first half mirror 25 is partially reflected upward and enters the focusing imaging optical system 7. The focusing optical system 7 includes a first half mirror 25, an autofocus second objective lens 26, an autofocus relay lens 27, a second pupil restriction mask 28, and an autofocus relay lens along the optical axis. 27, a cylindrical lens 29 and an autofocus CCD sensor 30 are provided. The infrared light Lf reflected by the first half mirror 25 is condensed by the second autofocus objective lens 26, converted into image forming light, and forms a slit image. The autofocus relay lenses 27, 27 relay the slit image (infrared light Lg) formed by the second autofocus objective lens 26, pass through a cylindrical lens 29, and capture an image of the autofocus CCD sensor 30. The slit image again. The second pupil restriction mask 28 is provided so as to shield half of the pupil from light, and the light-shielded area corresponds to the above-described area shielded by the first pupil restriction mask 24. . Further, the cylindrical lens 29 is a lens having a refracting action only in a predetermined direction, and compresses the infrared light Lg in a direction perpendicular to the plane of FIG. 1 (longitudinal direction of the slit image) in FIG. It functions to form an image on the imaging surface. Further, the autofocus CCD sensor 30 can be configured by a line sensor in which a plurality of light receiving units are arranged one-dimensionally, or an area sensor in which a plurality of light receiving units are arranged two-dimensionally.
[0019]
Next, a control system of the microscope will be described. The control system of the microscope drives an autofocus signal processing unit 31 for detecting a focus position, a stage driving unit 34 for moving the stage 11 up and down along the optical axis, and an electric revolver for exchanging the first objective lens. It comprises an electric revolver drive unit 35, a CPU 41 for controlling them, a memory 42, and an input unit 43.
[0020]
First, regarding the procedure of slit projection type autofocus control, a signal of a slit image detected by the autofocus CCD sensor 30 is output to the autofocus signal processing unit 31, processed by the CPU 41, and processed for the first objective lens. The focus position of the specimen is detected. The signal related to the focus position is sent to the stage drive unit 34 by the CPU 41, and the stage 11 is moved up and down along the optical axis direction to adjust the distance between the first objective lens 12 and the sample, thereby positioning the stage 11 at the focus position. . The position where the slit image is formed on the imaging surface of the auto-focus CCD sensor 30 is determined by the vertical movement of the stage 11 and the position of the sample or the cover glass 14 is changed. Move in the direction.
[0021]
The stage driving unit 34 includes a DC motor (not shown) attached to the stage 11, a motor driver for rotating the DC motor based on a vertical movement control signal and a speed control signal from the CPU 41, and a rotation angle of the DC motor. And an up / down counter for counting the vertical movement of the stage 11 based on the detection result of the rotary encoder. The count result of the up / down counter is output to the CPU 41 as a vertical movement position signal. When the DC motor rotates, the stage 11 moves up and down according to the rotation angle. The sample placed on the stage 11 also moves up and down together with the cover glass 14 and the slide glass 15, and the positional relationship between the sample and the first objective lens 12 is adjusted. Although not shown, the stage driving section 34 is provided with a limit sensor. The limit sensor is a sensor that detects a vertical movement limit point of the stage 11, and is provided to avoid contact between the first objective lens 12 and the cover glass 14.
[0022]
Although only one first objective lens 12 is shown in FIG. 1, the microscope of the present embodiment can be configured by a plurality of first objective lenses 12 having different magnifications. Although not shown, the plurality of first objective lenses 12 are mounted on an electric revolver, and the electric revolver is connected to an electric revolver driving unit 35 that drives the revolver to rotate. The electric revolver drive unit 35 includes a DC motor (not shown) attached to the electric revolver and a motor driver for rotating the DC motor based on a rotation control signal from the CPU 41. The electric revolver rotates according to the rotation of the DC motor. Then, the plurality of first objective lenses 12 mounted on the electric revolver also rotate, and any one of the first objective lenses 12 is positioned on the observation optical path of the microscope 10. The electric revolver driving unit 35 is provided with a sensor (not shown) for detecting the number (1 to 6) of the revolver holes positioned on the observation optical path of the microscope among the revolver holes (for example, six) of the electric revolver. Have been.
[0023]
Finally, the input unit 43 will be described. Although not shown, the input unit 43 is provided with a keyboard, an objective lens switch, an autofocus control start switch, a focus position storage switch, and an up / down fine adjustment switch.
[0024]
In the microscope of the present embodiment, the keyboard is used when inputting information of the first objective lens 12. Data relating to the first objective lens 12 input from the keyboard is stored in the memory 42. The focus position information stored by the focus position storage switch is also stored in the memory 42.
[0025]
The objective lens changeover switch is used when switching the first objective lens 12 positioned on the observation optical path of the microscope to another first objective lens 12. The CPU 41 controls the electric revolver driving unit 35 based on the switching signal input from the objective lens switching switch, and positions the revolver hole specified by the switching signal on the observation optical path of the observation optical system 3.
[0026]
The autofocus control start switch is used when instructing the start of the autofocus control in the microscope. When the auto focus control start switch is operated, the CPU 41 starts execution of the slit projection type auto focus control described above, the sample is positioned at the focus position of the first objective lens 12, and the slit projection type auto focus control is performed. Ends.
[0027]
The up / down fine adjustment switch is used when finely adjusting the vertical movement of the stage 11 by manual operation. The CPU 41 positions the stage 11 based on the fine adjustment signal input from the up / down fine adjustment switch. The operation of the up / down fine adjustment switch is performed by an operator while observing the image of the sample through the second eyepiece 13 and the eyepiece. When the operator can observe a high-contrast image satisfactorily, the operation of the up / down fine adjustment switch is terminated, and the stage 11 is positioned. At this time, in the microscope of the present embodiment, an arbitrary surface in the specimen matches the focal plane of the first objective lens 12.
[0028]
Next, the light-blocking filter 32 used in this embodiment will be described with reference to FIG. In the above description, the slit-shaped illumination light passes through the first objective lens 12 and irradiates the sample, but as shown in FIG. Is reflected and, depending on the type of the first objective lens 12, a material having a very high reflectance is used. The reflected light L0 is imaged on the autofocus CCD sensor 30 through the same path as the slit-shaped illumination light reflected by the sample described above, so that the first object is compared with the reflected light on the sample. If the light L0 reflected by the lens 12 is large, the autofocus control cannot be executed correctly.
[0029]
In this embodiment, in order to suppress the reflected light L0, a light-blocking filter 32 as shown in FIG. 4 is configured to be inserted between the collector lens 23 of the focusing illumination optical system 5 and the first pupil restriction mask 24. ing. The CPU 41 detects the first objective lens 12 disposed on the observation optical path of the observation optical system 3 from the sensor that detects the number of the revolver hole, and detects the information on the first objective lens stored in the memory 42. Then, it is determined whether it is necessary to shield the central portion of the slit-shaped illumination light, the attachment / detachment of the light shielding filter 32 is determined, and a control signal is output to the light shielding filter driving unit 33. Upon receiving the control signal, the light-shielding filter driving unit 33 attaches and detaches the light-shielding filter 32 according to the content of the control signal. The light shielding filter 32 is designed so as to shield only the central part of the slit illumination light as shown in FIG. 4 in consideration of the reflected light at the central part of the first objective lens 12. As a result, in a state where the light shielding filter 32 is inserted into the focusing illumination optical system 5, the slit-shaped illumination light applied to the sample has a shape shown in 22c. As shown in FIG. 5, the slit-shaped illumination light applied to the sample by the light-shielding filter 32 is incident on light other than the hatched portion, so that light near the optical axis is not reflected on the first objective lens 12. Is not incident on As a result, L0 reflected by the first objective lens 12 disappears due to the loss of the incident light, and does not affect the focusing imaging optical system 7.
[0030]
According to such a configuration, the light-shielding filter 32 is inserted to shield the slit-shaped illumination light at the center even if the lens strongly reflects the slit at the center depending on the type of the first objective lens 12 used. In the case of a lens with little reflection at the center, the slit-shaped illumination light can be used effectively by removing the light-shielding filter 32. Furthermore, since the light-shielding filter 32 can be automatically attached and detached depending on the type of the objective lens 12 to be used, the observer can observe the image without being conscious of the attachment / detachment of the light-shielding filter.
[0031]
Note that the present invention is not limited to the above embodiment. In the embodiment of the present invention, the light-blocking filter 32 for blocking the illumination light in the central portion is configured to be detachable between the collector lens 23 and the first pupil restriction mask 24. The same effect can be obtained even if it is configured to be detachable between the lenses 27, 27. According to such a configuration, the insertion position of the light shielding filter 32 can be selected in consideration of the structure of the microscope, so that the design of the microscope is facilitated.
[0032]
In the embodiment of the present invention, the information of the first objective lens 12 disposed on the observation optical path of the observation optical system 3 is obtained from the information of the sensor that detects the number of the revolver hole. The attachment / detachment was performed automatically, but the light-shielding filter drive unit 33 may be eliminated and the light-shielding filter 32 may be attached / detached manually. Further, the means for attaching and detaching may be eliminated, and the apparatus may be always inserted.
[0033]
Further, the same effect can be expected even if the light-shielding filter 32 and the first pupil restriction mask 24 are integrally formed and the illumination light near the optical axis of the LED light source 21 is shielded. FIG. 6 shows an embodiment in which the shape of the first pupil restriction mask 24 is changed to have the function of the light-blocking filter 32. 6A, the first pupil restriction mask 24 is formed slightly larger in the short direction of the slit opening 22a, and includes a center line extending in the longitudinal direction of the slit-shaped illumination light around the optical axis. 2 shows a case where light is shielded. Also, 22e in FIG. 6B shows a case where a semicircular protrusion is formed at a portion overlapping the optical axis of the first pupil restriction mask 24, and the central portion of the slit-like illumination light is shielded. I have. As described above, by adopting a configuration excluding the light-shielding filter driving unit 33, the structure can be simplified, the size can be reduced, and the control system can be simplified, and the cost can be reduced.
[0034]
In the above embodiment, the stage 11 is moved up and down along the optical axis in order to focus the sample 18 on the focal point of the first objective lens 12, but the stage 11 is fixed and includes the objective lens 12. It is also possible to adopt a configuration in which the observation optical system 3 moves up and down along the optical axis.
[0035]
【The invention's effect】
According to the slit projection type autofocus apparatus according to the present invention, the slit projection type illumination apparatus is provided with means for blocking the central part of the slit-shaped illumination light, and even if a lens that reflects the slit-shaped illumination light at the central part is used, the observation object can be controlled. To perform auto focus control.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a configuration of an optical system and a control system of a microscope according to an embodiment.
FIG. 2 is a diagram showing a configuration when a slit plate and a first pupil restriction mask are combined.
FIG. 3 is a diagram showing an optical path of slit-shaped illumination light incident on a sample.
FIG. 4 is a diagram showing the shape of a light shielding plate near the optical axis of slit-shaped illumination light.
FIG. 5 is a diagram illustrating a state of slit-shaped illumination light incident on a sample when the vicinity of the optical axis of the slit-shaped illumination light is shielded.
FIG. 6 is a diagram showing a shape when a first pupil restriction mask and a light shielding plate are integrally molded.
[Explanation of symbols]
5 Focusing illumination optical system 7 Focusing coupling optical system 12 First objective lens 21 LED light source 22 Slit plate 30 Autofocus CCD sensor 31 Autofocus signal processing unit 32 Light shielding filter 33 Light shielding filter driving unit 34 Stage driving unit 35 Electric Revolver drive unit 41 CPU

Claims (6)

A light source,
A slit plate with a slit formed,
After passing the light from the light source through the slit, a focus illumination optical system for irradiating an object through an objective lens to form an image of the slit on the object,
A focusing imaging optical system that receives reflected light of the image of the slit from the object through the objective lens and forms a reflected image of the image of the slit,
A photoelectric converter that is provided at an imaging position of the reflection image by the focusing imaging optical system and detects the reflection image,
Signal output means for outputting a signal for controlling the operation of the focus actuator based on the signal of the reflected image obtained by the photoelectric converter,
A slit projection type autofocus apparatus, comprising: a light shielding unit for shielding light that forms an image of the slit by being reflected at a central portion of the objective lens. The light shielding means,
The slit projection type autofocus apparatus according to claim 1, further comprising a light-shielding plate that shields light that forms an image of the slit by being reflected at a central portion of the objective lens. The light shielding plate,
The slit projection type autofocus apparatus according to claim 2, wherein the slit projection type autofocus apparatus is arranged and configured in the focus illumination optical system. The light shielding plate,
The slit projection type autofocus apparatus according to claim 2, wherein the slit projection type autofocus apparatus is provided by being arranged in the focusing imaging optical system. The slit projection type autofocus apparatus according to claim 2, further comprising a light shielding plate attaching / detaching unit for attaching and detaching the light shielding plate. The light shielding plate,
Detecting means for detecting the type of the objective lens,
6. The slit projection type autofocus apparatus according to claim 2, further comprising a light shielding plate attaching / detaching means for attaching / detaching the light shielding plate according to a type of the objective lens detected by the detection means.

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