JPH07101251B2 - Microscope autofocus device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope automatic focusing device, and more particularly to a microscope automatic focusing device for automatically focusing when observing an uneven material with a microscope.

[0002]

2. Description of the Related Art As a conventional microscope autofocus device of this type, for example, as shown in FIG. 4 as an explanatory view of its principle, Noriichi Arai et al., "Points of Design of Optical Pickup System", p. 157. , Nikkan Kogyo Gijutsu Center, (1984) has a microscope autofocus device.

The above-described microscope autofocus device shown in FIG.
In a microscope for magnifying and observing the document 1, in order to irradiate the document 1 with a collimated focusing light beam 3 through the objective lens 2 of the microscope at a predetermined angle, the central axis of the objective lens 2 is parallel to the optical axis of the microscope. Laser light source 4 for irradiating the focusing light beam bundle 3 toward the objective lens 2 by decentering it by a predetermined amount, and a light receiving lens for collecting the focusing light beam bundle 3 that has been reflected by the surface of the material 1 and passed through the objective lens 2. 6 and an optical position detecting element (hereinafter referred to as a light receiving element) which receives the focusing light beam bundle 3 condensed by the light receiving lens 6 and outputs a light receiving position signal a corresponding to the position of the center of gravity of the received focusing light beam bundle 3. (Abbreviated as PSD) 7 and a light receiving position signal a, a drive signal is output, and the center of gravity of the focusing light beam bundle 3 received by the PSD 7 is set at a predetermined position on the PSD 7. The stage 8 mounted with the article 1 so that the position configured to include a control unit 9 for moving the optical axis of the microscope.

The laser light source 4 irradiates the collimated focusing light beam bundle 3 in parallel with the optical axis of the microscope and decentered from the central axis of the objective lens 2. The focusing light beam bundle 3 is focused on the document 1 by the objective lens 2,
The light is reflected by, passes through the objective lens 2 again, is condensed by the light receiving lens 6, and is received on the PSD 7. At this time, the focusing light beam 3 is eccentrically incident on the objective lens 2, and
Since the irradiation is performed at an angle with respect to, the barycenter position of the focusing light beam bundle 3 received by the PSD 7 corresponding to the change in the distance between the material 1 and the objective lens 2 is the light receiving surface of the PSD 7 according to the principle of triangulation. Displace along.

If, for example, a PSD for one-dimensional detection manufactured by Hamamatsu Photonics Co., Ltd. is used as the PSD 7, it has a flat light-receiving surface formed along the longitudinal direction, and external outputs are provided near both ends in the longitudinal direction. Have electrodes for. Between these electrodes, there is a uniform resistance layer along the aforementioned longitudinal direction. Further, when a ray bundle is incident on the resistive layer from the outside, the energy of the ray bundle can be converted into an electric current and taken out from the electrode.

The energy of the light flux incident on the above-mentioned light receiving surface is divided into currents which are inversely proportional to the distance between the incident point and the electrodes, and can be extracted from the respective electrodes. Therefore, when a light flux enters the central portion of the above-mentioned two electrodes on the light-receiving surface from the outside, the current that can be extracted from each electrode is 0, and such a position on the light-receiving surface is set as the base point. Then, it is possible to output a current having a level corresponding to the distance between the position where the light beam is incident from the above-mentioned central part and the above-mentioned base point to the outside, and the polarity of the output current is the above-mentioned base point. On the other hand, if the incident point of the light beam is positive on one side, it can have a negative polarity when the light beam is incident on the opposite side of the aforementioned incident point with respect to the aforementioned base point.

The PSD 7 detects the position of the center of gravity and outputs a light receiving position signal a having a level corresponding to the distance from the base point to the light receiving position. The control unit 9 receives the light receiving position signal a, outputs a drive signal to the stage 8, moves the stage 8 in the optical axis direction of the microscope, and the center of gravity of the focusing light beam bundle 3 received by the PSD 7 is always at a predetermined position. Servo control is performed so that (that is, the light receiving position detection signal becomes 0). Automatic focusing is performed by setting this predetermined position in advance as the barycentric position of the focusing light beam bundle 3 received by the PSD 7 when the document 1 is in the in-focus position of the microscope.

[0008]

In the conventional microscope autofocusing apparatus described above, the laser beam bundle (focusing beam bundle) that is eccentrically incident on the objective lens is collimated light.
Since the focus position of the objective lens and the converging position of the focusing light beam are overlapped with each other, the beam diameter of the focusing light beam on the document surface is minutely narrowed. For example, when the numerical aperture is NA, in the case of an objective lens with NA = 0.8, the beam diameter is about 50 μm at the maximum. On the other hand, the field of view of the microscope is about 200 μm, so the focusing ray bundle is affected by the unevenness on the material, and only a part of the field of view is in focus. The inner image has the disadvantage that it is largely blurred.

An object of the present invention is to widen the beam width of a focusing light beam for illuminating a material, and detect the reflected light of the focusing light beam reflected from this beam width by the above-mentioned PSD to obtain an observation field of view. A microscope that can focus on an average position of the reflective surface of the material inside, to focus on a wide range within the observation field of view by the imaging lens, and can make the range of defocus smaller than before. An object is to provide an autofocus device.

[0010]

SUMMARY OF THE INVENTION A microscope autofocus device according to the present invention comprises an objective lens arranged in the vicinity of a material and an imaging lens arranged farther than the objective lens with respect to the material to generate a magnified image of the material. And a control unit that outputs the drive signal and a stage that is driven by a drive signal in a direction parallel to the optical axis of the objective lens and that places the material on the objective lens side. In a microscope that illuminates the material with a light source and generates a magnified image of the surface of the material with the imaging lens, a focusing light source that outputs a coherent focusing light flux, and a light flux of the focusing light source The ray bundle that is arranged on the front surface of the emitting portion and transmits a part of the focusing ray bundle and that is incident from a direction orthogonal to the traveling direction of the focusing ray bundle is reflected. A first beam splitter for transmitting and reflecting a part in the same direction as the focusing light beam bundle, and between the image forming lens and the objective lens on the side farther from the focus adjusting light source with respect to the first beam splitter. A part of the focusing light beam bundle that is arranged and reflected by the first beam splitter is reflected and directed toward the objective lens parallel to the optical axis of the objective lens and separated from the optical axis of the objective lens by a predetermined distance. A second beam splitter that reflects a part of the incident light beam and transmits the other part, and is inserted between the first beam splitter and the focus adjusting light source and in a direction parallel to the optical axis of the objective lens. Alignment in which the focusing light flux is converted into a predetermined divergent light with a predetermined interval and the diameter and spread angle are adjusted to a predetermined amount when the material is irradiated through the objective lens. A lens and a focusing ray bundle that has been reflected by the surface of the material in the focusing ray bundle and has passed through the objective lens and then reflected by the first and second beam splitters to receive a preset position. A position detection element that outputs a converted signal into an electric signal having a level proportional to the distance between the origin and the light receiving center of gravity in the light receiving position and a sign corresponding to the direction of the deviation from the origin to the light receiving center of gravity position, and The first beam splitter and the position detecting element are arranged between the first beam splitter and the first position detecting element.
A light-receiving lens for forming an image of a light beam incident on the position-detecting element on the position-detecting element, and an output of the light-receiving element as an input to output the drive signal to a predetermined position on the position-detecting element. And a control unit for driving and moving the stage parallel to the optical axis of the objective lens so that the image of the reflection component in the light beam for focusing is positioned.

[0011]

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

FIG. 1 is a block diagram showing an embodiment of a microscope autofocusing apparatus of the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention different from FIG. 3 is a principle diagram showing the operation of the present invention.

First, the principle of operation of the microscope autofocus device of the present invention will be described with reference to FIG. In FIG. 3, a laser light source 4 that generates and emits a collimated focusing light beam 3 is decentered from the optical axis Z of the objective lens 2 and installed at a position that does not interfere with the optical path between the objective lens 2 and the imaging lens 16. To do. At this time, the direction of the laser light source 4 is set so that the irradiation direction of the focusing light beam bundle 3 is parallel to the above-mentioned optical axis Z and is directed toward the objective lens 2. A matching lens 5 is inserted and arranged between the laser light source 4 and the objective lens 2. The focusing light beam 3 that has passed through the matching lens 5 is converted into divergent light by the matching lens 5 so that the width of the focusing light beam irradiated on the material 1 becomes a predetermined size. The focal length and the distance to the objective lens 2 are set in advance. Illumination light is separately applied to the surface of the material 1 from the outside, and a part of the light rays reflected from the material 1 in the illumination light passes through the objective lens 2 and reaches the imaging lens 16, and the imaging lens 16 To form a desired magnified image. The focusing light beam that has passed through the matching lens 5 passes through the objective lens 2 and illuminates the document 1 at a predetermined angle. A light receiving lens 6 that collects a light beam 3 for focusing that is reflected on the surface of the material 1 and that has passed through the objective lens 2 and collects it on a light collecting surface of a PSD 7, which will be described later, and a light beam bundle for focusing that is collected by the light receiving lens 6. PSD7 which is a position detecting element which receives 3 and outputs a light receiving position signal a corresponding to the position of the center of gravity of the received focusing light beam bundle 3, and a laser beam which is received by the PSD 7 based on the light receiving position signal a. (Focusing light beam bundle) 3 is configured to include a control unit 9 for moving the stage 8 on which the material 1 is placed in the optical axis (Z direction) of the microscope so that the position of the center of gravity of the focusing light beam 3 becomes a predetermined position. It

The focusing light beam 3 emitted from the laser light source 4 is condensed by the matching lens 5 in front of the objective lens 2 and has a predetermined diameter and divergence angle.
Incident on. Therefore, the focus position of the focusing light beam bundle 3 narrowed down by the objective lens 2 is deviated from the focus position of the objective lens 2 and is not focused on the document 1. The beam diameter on the document 1 at this time is determined by the arrangement of the matching lens 5,
The matching lens 5 is arranged so that the beam diameter on the document 1 at the focus position of the objective lens 2 becomes approximately the same as the field diameter of the microscope. The focusing light beam bundle 3 reflected by the material 1 passes through the objective lens 2 again, and is focused on the PSD 7 by the light receiving lens 6. At this time, the optical axis of the focusing light beam 3 is incident parallel to the optical axis Z of the microscope and decentered from the central axis of the objective lens 2, and the document 1 is illuminated at an angle. Due to the principle of surveying, the center of gravity of the focusing light beam bundle 3 received by the PSD 7 changes in the X direction shown in FIG. 3 in response to the change in the distance between the material 1 and the objective lens 2. Here, since the beam diameter of the light flux for focusing on the document 1 is about the same as the field diameter of the microscope, this barycentric position corresponds to the average height of the entire field of view. The PSD 7 detects the position of the center of gravity and outputs a light receiving position signal a having a polarity according to the distance between the reference point and the position of the center of gravity described above and the direction thereof. The controller 9 receives the light receiving position signal a and drives and moves the stage 8 in the optical axis direction of the microscope to perform servo control so that the center of gravity of the focusing light beam bundle 3 received by the PSD 7 is always at a predetermined position. . This predetermined position is the material 1
By previously setting the barycentric position of the focusing light beam bundle 3 received by the PSD 7 when is in the in-focus position of the microscope, it is possible to perform automatic focusing to the average height of the entire microscope field of view.

FIG. 1 is a block diagram showing an embodiment of a microscope autofocus device to which the present invention is applied.

As a laser light source 4, an infrared laser diode 10 and a collimating lens 11 generate a collimating focusing light beam bundle 3, and a matching lens 5 produces a beam of light when the focusing light beam bundle 3 enters the objective lens 2. Adjust the diameter and spread angle to the specified amounts.

The beam splitters 12 to 14, which will be described later, are
A part of the incident light is transmitted and the rest is reflected. For example, if the shape is a parallel plate and the incident angle of the light flux from the light source to be transmitted to the incident surface is 90 degrees, It is possible to reflect a light beam coming from a direction different from the light source of 90 degrees and direct it in the same direction as the traveling direction of the transmitted light.

A part of the focusing light beam bundle 3 is transmitted through the beam splitter 12, part of which is reflected by the beam splitter 13 and the beam splitter 14, and is incident on the objective lens 2. The focusing light flux 3 that has passed through the objective lens 2 is reflected by the reference material 1, passes through the objective lens 2 again, and is partially reflected in this order by the beam splitter 14, the beam splitter 13, and the beam splitter 12, and is collected by the light receiving lens 6. It is illuminated and the position of the center of gravity is detected by the PSD 7. The PSD 7 outputs this detection position as a light receiving position signal a, and the control unit 9 servo-controls the movement of the stage 8 in the optical axis direction of the microscope based on the light receiving position signal a to perform automatic focusing.

Part of the light beam emitted from the illumination light source 19 for illuminating the material 1 is transmitted through the beam splitter 13 and partially reflected by the beam splitter 14 to illuminate the material 1, and the objective lens 2, An image is formed by the imaging lens 16.

The formed optical image is taken by the taking lens 17
The optical image of the material 1 is magnified and picked up so that it can be detected by the CCD element 18, and is formed on the light-receiving surface of the CCD element 18.
At this time, a part of the focusing light beam bundle 3 reflected by the data 1 also passes through the beam splitter 14 and passes through the CCD element 18.
Therefore, the infrared cut filter 15 is arranged in front of the imaging lens 16 to allow only the imaging light to pass therethrough and cut the focusing light beam bundle 3.

In the above embodiment, the CCD element 18 detects the magnified image of the observed material 1.
If visual observation is to be performed, the photographic lens 17
And the CCD element 18 may be omitted. Further, in the above-described embodiment, the wavelength of the light beam emitted from the illumination light source 19 is different from the wavelength of the light beam emitted from the infrared laser diode 10. In the embodiment of FIG.
The position where the PSD 7 is arranged and the position where the infrared laser diode 10 is arranged are interchanged with each other, and the matching lens 5 is arranged between the infrared laser diode 10 and the beam splitter 12 and closer to the beam splitter 12. 5, the collimator lens 11 is arranged between the infrared laser diode 10 and the light receiving lens 6 between the PSD 7 and the beam splitter 12, and the same operation as that of the apparatus having the configuration of FIG. 1 is performed. It is clear that this is possible. In the embodiment of FIG. 2, the illumination light emitted from the illumination light source 19 shown in FIG. 1 is reflected by the beam splitter 13, and this reflected light is further transmitted by the beam splitter 14 via the objective lens 2 to the data 1 1 is arranged, and further, the infrared laser diode 10 is arranged at the position where the illumination light source 19 is arranged in FIG. 1, and the collimator lens 11 is arranged in front of the infrared laser diode 10, and A matching lens 5 and a beam splitter 12 are arranged between the beam splitter 13 and the collimator lens 11 in this order, and a component of the focusing light beam emitted from the infrared laser diode 10 that has passed through the beam splitter 12 is arranged. However, it is further transmitted through the beam splitter 13 and emitted from the above-mentioned illumination light source 19 and reflected by the beam splitter 13. Are arranged so that the light rays and parallel light rays. Further, in the embodiment of FIG. 2, in the above-mentioned focusing light beam bundle, the light beam is reflected by the reference material 1, transmitted through the objective lens 2, reflected by the beam splitter 14, transmitted through the beam splitter 13, and transmitted through the beam splitter 12. The light receiving lens 6 is arranged at a position for receiving the component reflected by, and the PSD 7 is arranged at a position where the component transmitted through the light receiving lens 6 comes to the light receiving surface.

The arrangement of components other than those described above is the same as that shown in FIG. As is clear from the above description, FIG.
The microscope auto-focusing device of this embodiment also operates similarly to the device of the embodiment shown in FIG.

Also in the embodiment of FIG. 2, the position of the infrared laser diode 10 and the position of the PSD 7 are replaced with each other, and the collimating lens 11 and the matching lens 5 are replaced with each other.
It is obvious that the infrared laser diode 10 may be arranged in this order from the emission port side of the light beam to the beam splitter 12 side, and the light receiving lens 6 may be arranged between the beam splitter 12 and the PSD 7.

Further, in FIG. 2, when the enlarged image of the document 1 is visually observed, the taking lens 17 and the CCD are used.
The element 18 can be omitted.

[0025]

According to the microscope autofocusing apparatus of the present invention, instead of eccentrically entering the collimated laser beam bundle for focusing, which is a laser beam, into the objective lens, a laser beam having a predetermined spread angle is eccentrically entered. , The beam diameter of the focusing light flux on the material can be made to be about the same as the field of view of the microscope, and automatic focusing is performed on the average height of the entire field of view without being affected by unevenness on the material. It has the effect that

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a microscope autofocus device of the present invention.

FIG. 2 is a block diagram showing an embodiment of a microscope autofocus device different from that of FIG.

FIG. 3 is a principle diagram showing an operation of the present invention.

FIG. 4 is a principle diagram showing the operation of a conventional microscope autofocus device of this type.

[Explanation of symbols]

 1 Reference Material 2 Objective Lens 5 Matching Lens 6 Photosensitive Lens 7 PSD 8 Stage 9 Control Section 10 Infrared Laser Diode 11 Collimating Lens 12 Beam Splitter 13 Beam Splitter 14 Beam Splitter 15 Infrared Cut Filter 16 Imaging Lens 17 Photographic Lens 18 CCD Element 19 Illumination light source

Claims (7)

[Claims] 1. An objective lens arranged in the vicinity of a material, and an imaging lens arranged farther from the objective lens with respect to the material to generate a magnified image of the material, and parallel to the optical axis of the objective lens. The surface of the material is enlarged by irradiating the material with a stage that is driven by a drive signal in any direction to place the material on the objective lens side and a control unit that outputs the drive signal, and irradiates the material with an irradiation light source added from the outside. In a microscope that produces an image by the imaging lens, a focusing light source that outputs a coherent focusing light flux, and a focusing light flux of the focusing light flux that is arranged in front of an exit portion of the focusing light flux A part of the light bundle that is transmitted from a direction orthogonal to the traveling direction of the focusing light bundle is partially transmitted and reflected in the same direction as the reflected focusing light bundle. A first beam splitter to
A part of the focusing light flux reflected by the first beam splitter, which is arranged between the imaging lens and the objective lens at a position farther from the focus adjusting light source with respect to the first beam splitter, is reflected. A second beam splitter that is parallel to the optical axis of the objective lens and is separated from the optical axis of the objective lens by a predetermined distance and reflects a part of a light beam that is incident on the objective lens and transmits the other part; The focusing beam bundle is inserted between the first beam splitter and the focus adjusting light source in a direction parallel to the optical axis of the objective lens and at a predetermined interval, and the focusing light beam bundle is converted into a predetermined divergent light beam to transform the objective light beam. A matching lens that adjusts the diameter and spread angle to a predetermined amount when the material is irradiated through the lens,
Within the focusing light beam bundle, the focusing light beam bundle reflected by the surface of the material and passing through the objective lens and then reflected by the first and second beam splitters is received, and a preset position is set as an origin. An optical position detecting element for converting and outputting an electrical signal having a level proportional to the distance between the origin and the light receiving center of gravity in the light receiving position and a code corresponding to the direction of deviation from the origin to the light receiving center of gravity, and A light receiving lens which is arranged between the first beam splitter and the optical position detecting element and forms an image of a light beam incident through the first beam splitter on the optical position detecting element; and an output of the optical position detecting element. Is input and the drive signal is output, and the stage is moved so that the image of the reflection component of the focusing light beam bundle is located at a predetermined position on the optical position detection element. Microscope autofocus apparatus characterized by a control unit that drives and moves in parallel to the optical axis of the objective lens. 2. An objective lens arranged in the vicinity of the material, and an imaging lens arranged farther from the objective lens with respect to the material to generate a magnified image of the material, and the objective lens of the objective lens according to a drive signal. In a microscope that is driven in a direction parallel to an optical axis and has a stage that mounts the material on the objective lens side, and irradiates the material with an irradiation light source that is separately added from the outside to generate a magnified image of the surface of the material, A focus adjustment light source that outputs a coherent focus light beam bundle, and is arranged in front of the emission part of the light beam bundle of the focus adjustment light source, reflects a part of the focus light beam bundle, and is orthogonal to the focus light beam bundle. A first beam splitter that transmits a light beam incident from a direction in a direction orthogonal to the incident direction of the focusing light beam bundle, and a pair of first beam splitter and the first beam splitter. Then, a part of the focusing light beam bundle that is arranged farther from the focus adjusting light source and that is reflected by the first beam splitter is reflected, and the objective lens is parallel to the optical axis of the objective lens at a predetermined interval. Is disposed between the first beam splitter and the focus adjustment light source, and a second beam splitter that reflects a part of a light beam that is incident on the objective lens away from the optical axis of The focusing light flux when the focusing light flux is converted into a predetermined divergent light in a direction parallel to the optical axis of the objective lens and at a predetermined interval and the material is irradiated through the objective lens. Lens for adjusting the beam diameter and divergence angle of the beam to a predetermined amount, and the second beam after passing through the objective lens after being reflected by the surface of the material in the focusing light beam bundle. A ray bundle transmitted from the first beam splitter after being reflected by the splitter is received and a preset position is set as an origin, and a level proportional to the distance between the origin and the light receiving center of gravity in the light receiving position and the light receiving center of gravity position from the origin. Up to an optical position detecting element for converting and outputting an electric signal with a code corresponding to the direction of the shift, and the first beam splitter inserted between the optical position detecting element and the first beam splitter. A light-receiving lens that collects a part of the transmitted light flux for focusing and forms an image on the light-position detecting element, and the output of the light-receiving element as an input to the light-receiving element for focusing at a predetermined position on the light-receiving element. A control unit that outputs the drive signal for driving and moving the stage parallel to the optical axis of the objective lens so that the image of the reflection component in the light beam bundle is positioned. Microscope autofocus apparatus characterized. 3. The microscope according to claim 1, wherein the laser light source for generating and emitting infrared light and the collimator lens arranged immediately before the irradiation opening of the laser diode constitute the focus adjusting light source. Autofocus device. 4. The microscope according to claim 2, wherein the laser light source for generating and emitting infrared light and the collimator lens arranged immediately before the irradiation opening of the laser diode constitute the focus adjusting light source. Autofocus device. 5. The microscope auto-focusing device according to claim 1, wherein the focusing light emitted from the focusing light source is provided between the imaging lens and the second beam splitter. A microscope auto-focusing device, which is provided with an optical filter for blocking transmission of a light beam bundle. 6. The microscope autofocusing device according to claim 1, wherein the microscope autofocusing device is inserted between the first and second beam splitters and transmits or reflects through the first beam splitter. A part of the incident light beam reflected and directed toward the second beam splitter, and a part of the light beam incident from the direction orthogonal to the incident light beam transmitted and directed toward the second beam splitter. The beam splitter and the third beam splitter are arranged on the side opposite to the second beam splitter with respect to the third beam splitter so that the light flux transmitted by the third beam splitter is directed to the second beam splitter. An automatic focusing device for a microscope, comprising: a light source for illumination that generates and emits a luminous flux for use. 7. The microscope autofocusing apparatus according to claim 1, wherein the microscope autofocusing apparatus is inserted between the first and second beam splitters and transmits or reflects through the first beam splitter. And a part of the incident light beam is transmitted to the second beam splitter and directed toward the second beam splitter, and a part of the light beam incident from a direction orthogonal to the incident light beam is reflected to the second beam splitter. Of the beam splitter and the third beam splitter, and the luminous flux reflected by the third beam splitter is arranged on the side opposite to the second beam splitter with respect to the third beam splitter so as to illuminate the third beam splitter. An automatic focusing device for a microscope, comprising: a light source for illumination that generates and emits a luminous flux for use.